Some med cross-examine oblige please!?

Please help me swot which of these answers are correct:

The number and kind of diagnostic trial allowed for a condition is determined by:

A: Doctors only.
B: organization regulations only
C: insurance companies solitary
D: Doctors, government regulations, insurance companies and MCO's

I thinking it's perchance A but could be D

What do you think?

TIA

Answers:   The answer should be "a", but the answer to your query is "d".

In reality, the answer is pretty much "b & c" because sometimes not even your dr can return with a test approved for a merciful. Its ridiculous that a dr should have to phone an insurance company to see what tests he/she can run or what medication he/she can prescribe for their patients. It should be the other way around.
D

It should be doctors, but since the insurance companies hold the purse strings.