I would say C is the most correct.
In D it depends on what water source you're using. Let's say it is a waterfall, then the source of the water (melting ice or a lake) may disappear in the future.
If you're using underwater "windmills" placed in the ocean, then you would expect it to last a while as the ocean will not disappear in the near future.
Answer:
b. 1.5 atm.
Explanation:
Hello!
In this case, since the undergoing chemical reaction suggests that two moles of A react with one moles of B to produce two moles of C, for the final pressure we can write:

Now, if we introduce the stoichiometry, and the change in the pressure
we can write:

Nevertheless, since the reaction goes to completion, all A is consumed and there is a leftover of B, and that consumed A is:

Thus, the final pressure is:

Therefore the answer is b. 1.5 atm.
Best regards!
Answer: the answer is c.The unbalanced push causes the cart to speed up.
Explanation:
The application of an unbalanced force (the push) causes the cart to speed up. When the cart is in constant motion, the forces are balanced and there is no speeding up. Once an unbalanced force is added, the cart's speed changes.