The correct option is
C defer
Option C: 'Precipitate' means 'cause to happen suddenly, unexpectedly, or before the expected time'.
'Defer' means 'put off to a later time, postpone'.
As you can see, 'defer' means the opposite of 'precipitate'.
Hence option C is correct.
Option A: 'Pull' means 'move something towards yourself'.
Option B: 'Push' means 'to move something away from yourself'.
Option D: 'Create' means 'to make something new'.
Option E: 'Aggravate' means 'to make worse or more serious'.
These words do not mean the opposite of the given word.
Hence options A, B, D and E are wrong.