I think that it is c just because it seems to fit the sentence
<span>c. telling her how he built their bed</span>
There were 15 people total
“About Mars” is the Adjective Phrase.
Adjective phrase describes “what kind of which ones”
So for example here
“After school, I looked for books about Mars.”
“About Mars” describes the kind of books so that makes it an Adjective phrase.
I hope this helps.
