A recent study has found that within the past few years, many doctors

Hi

Let me try to address your query:

When assessing parallelism, it helps to consider the sentence as a mathematical expression with parentheses. We have some leeway in where to place the parentheses, but, as in a mathematical operation, the terms outside the parentheses must be applied to every term inside upon expansion. Let us consider an example.

At the next meeting, the company directors will (assess the yearly plan, discuss the compensation policy, and make a final decision regarding closure of the Bosnian operations).

Note the placement of the parentheses - on expansion, the portion outside, "directors will", needs to be applied to each item inside ie; "assess...", "discuss..." and "make...". This is a correct construction and it maintains parallelism. Alternatively, we could also have:

At the next meeting, the company directors (will assess the yearly plan, will discuss the compensation policy, and will make a final decision regarding closure of the Bosnian operations).

Here, the parentheses are applied after "directors", which must now be applied to every item inside ie; "will assess...", "will discuss..." and "will make...". This construction is also correct and maintains parallelism.

Similarly in option (E), parallelism can be maintained either by having "to" precede both "retire" and "face", as you have put it. In this case, the parentheses open before the "to", as below:

A recent study has found that within the past few years, many doctors have elected (to retire early rather than to face) the threats of lawsuits and the rising costs of malpractice insurance.

Parallelism is also maintained as given in the option, in which case the parentheses open after the "to":

A recent study has found that within the past few years, many doctors have elected to (retire early rather than face) the threats of lawsuits and the rising costs of malpractice insurance.

Hope this helps.