It's not ____ cheap, but high quality too.

• A. only
• B. very
• C. quite
• D. so

Answer: (A)

The idea being tested is using the correlative structure not only ... but ... to show two positive qualities at once. In this sentence, you want to say something is both cheap and high quality. The natural way to do that is: it’s not only cheap, but high quality too. The word after not is only, which completes the common expression and clearly links the two favorable traits.

Other options don’t fit as well. not very cheap would imply it isn’t cheap at all, which clashes with calling it cheap. not quite cheap suggests it’s almost not cheap, which again changes the meaning. not so cheap would mean it isn’t cheap, which again contradicts the intended sense of having two good qualities together.