A synthesis reaction is a reaction between at least two compounds in which?

Question

A. one breaks down into at least two products
B. a compound is decomposed by an electric current
C. a compound burns in the presence of oxygen
D. a new, more complex compound is formed

Answer 1

Letter "D" is correct.

A synthesis reaction (aka combination or compostition reaction) is one where you start with at least two reactants and end with one product. The multiple reactants join to form a product with much larger complex molecules.

Answer 2

D, To synthesize is to create or to make bigger.