Answer:
D. hot, but much cooler than at a hydrothermal vent
Explanation:
A cold seep is an area in the ocean floor where hydrogen sulfide, methane and other hydrocarbon rich fluids seep through thus forming a brine pool.
A cold seep is also called a cold vent and its temperature is not necessary lower than that of the surrounding water, but it is lower than that of a hydrothermal vent which is about 60 °C.
I am pretty sure the answer is increase and increase. Because enzymes are affected by changes in pH. The most favorable pH value - the point where the enzyme is most active - is known as the optimum pH. Extremely high or low pH values generally result in complete loss of activity for most enzymes.