Answer:
The correct option is E
Step-by-step explanation:
Option A is wrong because there should be two companies needed for a merger, but this option makes it look like it's just one company "gas and electric company is". For example, Procter and Gamble company is not a merger.
Option B is also wrong because if it is a merger then "are" in "and electric companies are" makes it wrong.
Option C has the same error as option B
Option D has the same error as option B
Option E is the correct option because it eliminates the error in Option A; the merger of the nation's leading "gas company and electric company " and also eliminates the error in option B, C, and D, replacing "are" with "is".