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.

it is very hard for the climatologists to precisely predict how will the global temperatures be changing so there's lots of models, some of which differ significantly, this is due to multiple factors, and probably the most important is the human activity.

humans have been a key factor in climate change around the globe since the start of the industrial revolution, and in the past few decades the consequences are becoming more obvious. there's lots of emission of pollutants in the atmosphere as well as changing the environment on the surface itself, so it's really hard to predict how will that go in the future because there's some countries that are reducing the damage and are going towards green energy, while others are stubbornly continuing with pollution and damages to the environment.