Final answer:
The volume of the rock is 25 mL, which is equal to the volume of water displaced when the rock was submerged in the graduated cylinder.
Step-by-step explanation:
You asked about the volume of a rock based on the increase in water level when it is submerged in a graduated cylinder. If the water level increased by 25 mL when the rock was dropped into the water, the volume of the rock is equal to the volume of the displaced water. Therefore, the volume of the rock is 25 mL, making the correct answer a- 25 mL.