The noun in this sentence which is uncountable, meaning that it names something that cannot be counted is the noun water.
You cannot count how many waters there are - it is uncountable. The other nouns, students and pitcher are countable, so they cannot be the correct answers, but rather water is.
Can you give me some more information. I am not able to understand the question.
Answer:
ask someone els i don't know this one
Explanation:
I think the answer is number one