Deposition means the process of accumulation of sediment. Its opposite is the process of eroding.

To deride means to ridicule, to insult. Its opposite among the choices is to show respect for.

To desiccate means to dehydrate, to remove water from. Its opposite is to add water to.

Derelict means a social outcast, a tramp. Its opposite among the choices is a pillar of society.

The opposite of  desiccate is to drench.

The opposite of to desiccate among the choices is to hydrate.

Desultory means aimless, without goal or method. Its opposite is strictly methodical.

Desuetude means disuse, no longer in use. Its opposite is use.

Detumescent means lessening of a swelling. Its opposite is swollen. 

Diatribe means violent criticism. Its opposite is encomium.

Deterioration means reduction in quality or value. Its opposite is improvement.

The opposite of diatribe is eulogy.

The opposite of diatribe is complimentary description.

The opposite of to dilute is to concentrate.

The opposite of din is silence.

Dilettante means a dabbler. Its opposite is connoisseur.

Diffident means shy. Its opposite is bold.

Diminutive means very small, microscopic. Its opposite is immense.

To disabuse means to free from error. Its opposite is to lead into error.

To dilate means to enlarge. Its opposite is to narrow.

Discrete means discontinuous. Its opposite is continuous.

Din means uproar, noise. Its opposite is hush.

To disarm means to win over. Its opposite is to challenge.

To disaffect means to offend. Its opposite is to win over.

The opposite of disabuse is to deceive.