Answer:
B. Time spent on the beach
Explanation:
Given is -
On a beach, there is a positive correlation between the number of bottles of water a person drank and the number of whales they spotted.
Positive correlation is defined as a positive relation between two entities, that change with each other. If the value of one changes, the second also changes.
So, the best possible answer is option B.
This is because, when we spend more time on the beach, the more thirsty we get and more water is consumed. And if we spend more time on the beach, then there are more chances that more whales might pop out of the sea.