How does abscisic acid acts antagonistically to auxin and gibberellins ?

Dear student,

Abscisic acid acts antagonistically to auxin and gibberellins as - 
Auxin and gibberellins initiate the shoot apical and root apical system in a plant and help in a plant to grow whereas, abscisic acid is responsible for retention of seed into a dormant state, inhibits the growth of a plant, hence antagonistic to auxin and gibberellins.

Regards.