3. Some bat caves, like honeybee hives, have residents that take on different duties such as defending the entrance, acting as sentinels and to sound a warning at the approach of danger, and scouting outside the cave for new food and roosting sites.
(A) acting as sentinels and to sound
(B) acting as sentinels and sounding
(C) to act as sentinels and sound
(D) to act as sentinels and to sound（B）
(E) to act as a sentinel sounding
这里由于结构平行选B,但是这样整个句子的结构就是such as defending....,acting as...and sounding....,and scouting....and roosting.....我想请问一下，这里的acting as...and sounding....,是做伴随状语修饰前面吗，还有such as doing A ,doing B ,and doing C ,zh这里怎么这么多ＡＮＤ啊 | 
