Read the sentence. The cow chewed contentedly on grass trimmed that morning. What is the participial phrase, and which word does it modify?
chewed contentedly; modifies cow
contentedly on grass; modifies cow
trimmed that morning; modifies grass
on grass; modifies chewed
and NO MEADOWS.

the speaker versus the boy.

the correct answer is option d. none of these. it is noted that options a, b, and c share the same content.

despite the valid answer provided at the last sentence of each of the options, a question/answer format shouldn't include humourous themed responses such as "you bet your thermal pj's we do." - unless of course, the answer is carried out in an informal environment. this could be replaced with a simple "yes" or "it is necessary".

the question should be re-phrased to a more appropiate syntaxis. instead of "do we need the greenhouse effect? ", it should be written as "is the greenhouse effect necessary? " in order to give it a general scope, instead of limiting the answer to the needs of "we" the humans.