The answer is B, this is a synthesis reaction. A good way to identify a synthesis reaction is when there are multiple reactants, but only one product.
Compound are formed by two or more elements chemically combined. For example: H^2O is the water formula, this is a compound because you two elements which are Hydrogen and Oxygen and together they form a compound. The (^2) is the amount of atoms the formula has, in this case Hydrogen has two atoms and Oxygen is neutral.
Note that
1 m = 3.2808 ft
Therefore
1 km = 3280.8 ft
and

Answer: 1.0682 x 10⁵ ft/hr