Official Explanation:What does the sentence mean - This sentence shows a contrast between Arbor day celebration in the past and current time.
1: In the past = More than a million trees were planted in Nebraska.
2: In present = It is observed throughout the nation and the world.
It appears that the point of contrast is the location of celebration of Arbor day.
What does the question test - This question tests your expertise in establishing correct comparison/contrast.
What are the errors in the original sentence – The original sentence has parallelism error since the contrast is not established correctly. As explained in the meaning, the emphasis of the sentence is that in the past, it was celebrated such that more than million trees were planted. In order to establish correct contrast, emphasis should be placed on the location where Arbor Day was celebrated.
a) Whereas, when first observed, more than a million trees were planted in Nebraska on Arbor Day, it is now observed throughout the nation and the world.
This choice does not establish correct comparison as explained in sentence analysis.
b) Whereas, Arbor Day was first observed with the planting of more than a million trees in Nebraska, now the entire nation and the world observe Arbor Day.
This choice has two parallelism based errors:
1: Comparison error as in Choice A.
2: Parallelism Error – The two parallel (contrasting) clauses should be parallel and hence should be stated in same voice. But clause 1 – Arbor day was observed – is in passive voice and clause 2 – entire nation observe – is in active voice.
c) Whereas, Arbor Day was first observed in Nebraska with the plantation of more than a million trees, it is now observed throughout the nation and the world.
Correct Choice
d) Whereas, Arbor Day was first observed with the planting of more than a million trees in Nebraska, now the entire nation and the world observes Arbor Day.
This choice has three errors
1: Parallelism errors as explained in Choice B
2: SV-Number error – entire nation and world is plural subject and hence use of singular “observes” is incorrect.
e) Whereas, Arbor Day was first observed along with the plantation of more than a million trees in Nebraska, now the entire nation and the world observe Arbor Day
This choice has parallelism errors as explained in Choice B.
It also changes the meaning of the sentence by stating “arbor day was first observed along with the plantation of…”. This implies as if “Arbor day” and “plantation of trees” are two separate events that took place in Nebraska.