The diamond ring that her boyfriend bought for her turned . . . . . . . . to be a fake one. A. out B. upon C. with D. none

out
upon
with
none

The correct answer is A. The word “out” is the most logical choice in this sentence because it means “to become known or revealed.” In this case, the fact that the diamond ring was fake was not known at first, but it was later revealed to be a fake. The other options do not make sense in this context. The word “upon” means “on or at the surface of.” The word “with” means “in the company of.” The word “none” means “not any.”

Here is a possible rephrasing of the sentence:

The diamond ring that her boyfriend bought for her turned out to be a fake.