Answer:
C. The volume is 1/8 the original volume
Step-by-step explanation:
Step 1. To find how the volume changes if the diameter is reduced to one-half of the original size, we will test two scenarios:
• In the first scenario, the diameter will be 2, and in the second scenario, the diameter will be one-half of 2 which is 1.
We will find the volume for these two cases and see how it changes.
Step 2. For a diameter of d=2.
If the diameter is 2, the radius is:

Using the volume formula for a sphere:

In this case:

We will call this volume, V1:

Step 3. Now we will find the volume for the second case in which the diameter is d=1.
The radius is:

Using the same formula for the volume:

Solving the operations:

We will call this V2:

Step 4. As you can see, the first part of the previous expression is V1:

Therefore:

The second volume is the first volume multiplyed by 1/8 ⇒ it is 1/8 of the original volume.
Answer:
C. The volume is 1/8 the original volume