In which sentence is the nonessential clause underlined? a) the man leaning against the wall is from the zoo. b) the snake that he is holding is not poisionous c) its coloring, which is brown and green, allows it to hide in marshy areas. d) that snake slithering behind the rock is actually harmless. in which sentence is the essential clause underlined a) eve's sister, who loves opera, took her to a performance. b) eve, holding her program, waited for the curtain to go up. c) the soprano, visiting from canada, had long black hair. d) the person who sells souvenirs is in the lobby.

The nonessential clause is underlined in sentence c) Its coloring, which is brown and green, allows it to hide in marshy areas.

The underlined clause in this sentence is a non-defining relative clause, which only adds information about the noun phrase it modifies. Without the clause, the sentence is still gramatically correct and the meaning of the sentence does not change. Furthermore, non-defining relative clauses have to be written between commas.

The essential clause is underlines in sentence d) The person who sells souvenirs is in the lobby.

The underlined clause in this sentence is a defining relative clause, which gives essential information about the noun phrase it modifies. Without the clause, the meaning of the sentence changes (it is no longer a specific person the sentence is talking about). Furthermore, defining relative clauses are never writteng between commas.

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.