GMAT Critical Reasoning (CR) | Re: In order to raise revenue, the federal government planned a

Hi,

Initially, I arrived at E by POE - I did not find other options convincing enough to strengthen the argument. Only after I got to know that E is the OE, I reasoned it as below
Please check if my approach as described below is fine. Also please share if I am missing anything in this problem.

Reading the stem it's a 'if true' question and is asking which of the options would most 'contribute' to an explanation of XYZ. It's a strengthen question. Let's read the argument.
Govt. has introduced