The phrase in the parenthesis is acting as an adjective.
Nwoye likes the story of the Earth and the sky because it is one of his mother's favorite stories.
Answer:
The flight crew <em><u>are</u></em> attentive to the passengers.
<em>(</em><em>you have already given the explanation.</em><em>)</em>
As crew is a collective noun your answer will be are .
