Respuesta :
We went to a grocery store to see if there was an apple pie to purchase and enjoy.
an is the correct answer as before any word starting with vowel we use an and not a ...so an must be used in the sentence and after completion sentence will be
we went to *a*grocery store to see if there was **an**apple pie to purchase *and* enjoy
we went to *a*grocery store to see if there was **an**apple pie to purchase *and* enjoy