Answer:
<em>(c) a straight line with positive slope.</em>
Step-by-step explanation:
<u>Functions</u>
We are required to find a function that relates the height of the water in a cup to the volume of water in the cup.
The cup has a shape of a cone open upwards. The volume of a cone of height h and radius r is

This function relates the height with the volume, to find the required function, let's solve for h

Rearranging

Being all the values positive, the height and the volume are linearly related with positive slope
Answer: (c) a straight line with positive slope.