GMAT Sentence Correction (SC) | A recent study has found that within the past few years,

Tip : Usage of "Rather than" means preference of one over another and Usage of "instead of" means replacing one thing with another.Moreover instead of can only be used in case of Noun and verbs or actions so in below only

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

(A) had elected early retirement rather than face ---no two actions are there so usage of had not correct.