Judge the following sentence according to the criteria given below: marine invertebrates such as worms, mussels,
and octopuses have not had to evolve special mechanisms to maintain their body fluids at a proper concentrations
because their body fluids are nearly isotonic.
a) the assertion and the reason are both correct, and the reason is valid.
b) the assertion and the reason are both correct, but the reason is invalid.
c) the assertion is correct, but the reason is incorrect.
d) the assertion is incorrect, but the reason is correct.
e) both the assertion and the reason are incorrect.