Concept:The correct word is the one that forms a natural and fixed collocation with the noun "thirst."
Explanation:The word "quench" means to satisfy or relieve a strong need, especially thirst.
In standard English usage, the common expression is "quench one's thirst."
The other options do not fit the same idiomatic pattern.
"Wet" means to make something moist.
"Cool" means to lower the temperature.
"Soak" means to leave something in liquid for a time.
None of these words is naturally used with "thirst" in this sense.
Therefore, "quench" is the only option that correctly completes the sentence.
Answer:B. quench