Student or Learner
Here is an __________.
(A)one-year-old boy (B)open door (C)ugly dog and cat (D) Amy's angry sister
Q:The answer is (B), why not (A) or (D)
"An" indicates that the next word starts with a vowel sound, so "one" [wun] cannot be the next word, and you would not refer to someone as "an Amy's..", but "Amy's sister. So the only two possibilities are "open" and "ugly". However, since the verb is singular, there is only one object involved, which reduced the choice to "open door".