Emissivityis a measure of how much thermal radiation a body emits to its environment. On the other hand we have that reflectivity is a measure of how much is reflected, and transmissivity is a measure of how much passes through the object. If a body is required to be ideally reflective to its maximum efficiency, the body should NOT have the property of transmissivity or emissivity. Therefore it should be 0 its emittivity.
Correct answer would be A : ZERO.