Select the number of the punctuation error. The lobbyists1 spent a great deal of time, effort,2 and money in educating the legislators about the problems of the aged,3 therefore,4 the bill passed without difficulty.

2

Explanation:

When listing items in a sentence, you don't need a comma before the "and".

For example:

My favourite fruits are bananas, mangoes, cherries, pineapples and apples.

Hope that helped : )

b. failure at least that one seems the most negative out of all of the answers provided pls correct me if i'm wrong. : ))