Question

In the combustion of ethane, what is/are the reactant(s)?
A. CO2 and H2O
B. C2H6 and O2
C. O2 and H2O
D. CO2 and C2H6

Answer 1

Reactant are those that combine or reacts to give products !!

so in combustion of ethane ; ethane and o2 are reactants so ... your answer is B !!

Answer 2

Organic matter usually produce Carbon Dioxide and Water as its products. 
Answer is A for products.
Reactants will be ethane and oxygen
Ethane has 2 carbons. so B is the answer.