Answer:
dripping
Explanation:
Here, the current action of the water has something to do with "drip". Remember that a "gerund" is a word that pairs with a verb but actually acts like a noun. Gerunds usually end in "-ing".
In this sentence, "is" is the verb, and so it's very likely that we need to use the gerund of "drip" here. The gerund of "drip" is just "dripping".
So the answer is "dripping".
