To aggrandize means to make greater, more powerful. Its opposite is to render helpless. 

To aggravate means to worsen, to intensify, to exacerbate. Its opposite is to alleviate.

Aggregate means totality, entirety. Its opposite is isolated units.

To agitate means to shake up, to disquiet. Its opposite is to soothe which means to soften.

Agility means the ability to move quickly and easily. Its opposite is tardiness, which means slowness in motion or action.

Alacrity means prompt and cheerful willingness. Its opposite is hesitance and reluctance.

To alienate means to estrange, to disunite. Its opposite is to reunite.

An ally means a friend, a supporter. Its opposite is an adversary.

To alleviate means to make easier to bear. Its opposite is to exacerbate.

To amortise means to set apart money regularly to pay up a debt. Its opposite among the choices is to add to one's debts.  

Analgesia means the absence of the sense of pain. Its opposite is sensitivity to pain.

Analogous means similar. Its opposite is lacking similarity.

To amplify means to expand. Its opposite is to contract.

To analyse means to dissect, to disintegrate. Its opposite is to compound.

To amalgamate means to mix, to unite. Its opposite is to isolate.

To amalgamate means to combine. Its opposite is to separate.

To anchor means to fix firmly, to fasten. Its opposite is to dislodge.

Anarchy means bedlam, confusion. Its opposite among the choices is order.

Anguish means agony, great grief. Its opposite is happiness.

Anhydrous means dry. Its opposite is wet.

Animus means ill-will. Its opposite is goodwill.

Anomalous means abnormal. Its opposite is normal.

The opposite of anomalous is conforming to an established rule.

Anomaly means abnormality. Its opposite is conformity to norms.

The opposite of anomaly is predicted occurrence.