Out of the choices given, active and passive transport of solutes across a membrane typically differ because active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy. The correct answer is B.
B. Because of the presence of hydrogen sulphide in Brass, it combines with oxygen in air and form water, evaporates. So remained sulphide is colourless in air .So Brass gets discoloured in the air.
The answer could be either B or D. Both are important for marine biology. I would have to say D is the best answer though!
