Can anyone explain as to why E is the best...
1. "perceived as / perceive as" is correct idiom. So, "perceived to be" or "perceive being" are wrong. So "A" and "C" are out.
2. Now, "The Audubon Society and other conservation groups, concerned..." - the phrase starting with "concerned over what they..." is a Past Participle Phrase which modify "The Audubon Society and other conservation groups". So you can treat this phrase separate from the main sentence.
The main sentence (or clause) is this - "The Audubon Society and other conservation groups are preparing for a major political effort.", which is in present continuous tense.
So we need present tense at verb perceive
"perceive as" is a single idiom and the 2nd "as" at the end of the choice - B: underlined part is folly. - So consider these two reasons and make B out.
3. Out of "D" and "E" - D is wrong bcoz "serious threatening" is wrong serious is an adjective and so the correct is "threat" and not "threatening"
Perseverance, Hard Work and self confidence