Gender-based violence refers to the intentional use of physical, sexual, or psychological force against a person based on their gender. It is a form of discrimination that disproportionately affects women and girls in conflict settings.

Resolution 1325, adopted in 2000, is the landmark UN Security Council resolution that recognizes the importance of women's participation in peace and security processes and calls for increased efforts to protect women and girls from violence in conflict.

Gender mainstreaming is the process of integrating a gender perspective into all aspects of peacebuilding efforts, including policy development, program design, implementation, and monitoring and evaluation. It aims to ensure that gender equality is promoted and that the needs and perspectives of women and girls are taken into account.

While economic empowerment of women is an important goal, it is not a key pillar of the Women, Peace, and Security agenda. The key pillars are prevention of conflict, participation of women in peace processes, and protection of women and girls from violence.

Gender-based climate change refers to the disproportionate impact of climate change on women and girls. This is due to a number of factors, including women's and girls' limited access to resources, their increased vulnerability to violence, and their traditional roles in society.

Equal pay for equal work is not a challenge faced by women peacebuilders. The other options are all challenges that women peacebuilders face, including lack of access to resources, stereotypes and discrimination, and limited participation in decision-making.

Peacebuilding is the process of addressing the root causes of conflict and building sustainable peace. It involves a wide range of activities, including promoting human rights, supporting democratic institutions, and addressing economic and social inequalities.

Use of military force is not a key element of a gender-responsive approach to security. The other options are all key elements, as they address the specific needs and vulnerabilities of women and girls in conflict and post-conflict settings.

Demobilization is the process of disarming and demobilizing combatants after a conflict. It is a key part of the peacebuilding process, as it helps to reduce the risk of renewed violence and create a more stable environment.

Equal pay for equal work is not a key challenge to achieving gender equality in peace and security. The other options are all key challenges, as they prevent women from fully participating in society and contributing to peace and security.

Post-conflict reconstruction is the process of rebuilding infrastructure and institutions after a conflict. It is a complex and challenging process that requires a coordinated effort from a variety of stakeholders.

Use of military force is not a key element of a gender-responsive approach to post-conflict reconstruction. The other options are all key elements, as they help to ensure that the needs of women and girls are met and that they are able to participate fully in the reconstruction process.

Reintegration is the process of integrating former combatants into society after a conflict. It is a key part of the peacebuilding process, as it helps to reduce the risk of renewed violence and create a more stable environment.

Equal pay for equal work is not a key challenge to achieving gender equality in post-conflict reconstruction. The other options are all key challenges, as they prevent women from fully participating in society and contributing to peace and security.

Peacebuilding is the process of promoting human rights and democratic institutions in a post-conflict society. It is a complex and challenging process that requires a coordinated effort from a variety of stakeholders.