<em> </em><em>This </em><em>sentence </em><em>i</em><em>s</em><em> </em><em>in</em><em> </em><em>active</em><em> </em><em>voice</em><em>.</em>
C is the answer. Because he states Too quick for groan or sigh its not A because they curse him with their eyes it wasn't a real curse, Its not B because they turned their face with a ghastly pang, Its not D because they died but they still made thumping sounds.
I believe that the answer is b. To inform
Hope this helps.