2h2 + o2 --> 2h2o can be classified as what type of reaction? a. both synthesis and combustion. b. only synthesis c. only combustion d. it cannot be classified.

I believe the answer is B. Only synthesis.

The given equation is classified as a SYNTHESIS reaction wherein two simpler molecules, H2 and O2, combine to form a more complex one which is water (H2O). Further, this can also be classified as the combustion of hydrogen gas. The answer is letter A.