Explanation:

Let’s break this down:

- The question: How long does it take (in seconds) for a cylindrical armature to make 360° (one full turn)?

- Statement I: The armature has a 5-inch diameter.

- Does this help? Not really. The diameter doesn’t tell us how fast it’s spinning.

- Statement II: The armature spins at 120 revolutions per minute.

- This is useful: We know how many revolutions it makes per minute, so we can definitely compute the time for one revolution. (360° is one full rotation.)

Now, about the options:

- Option 1: You can answer the question using only one of the statements, not both.

- This fits: only II works.

- Option 2: Either I or II alone works.

- Nope. I alone won’t get you there.

- Option 3: You need both statements together, not either alone.

- Not true; statement II alone is enough.

- Option 4: You can’t answer even with both together.

- Not true; we absolutely can answer with II.

So, to spell it out:

The answer is option 1.

Statement II alone is sufficient. Statement I is not.

A green tick for confidence:

Option:1-1