Thanks, Jerry. I understand your approach. Let's try my question this way.

When do you apply E3605.4.1 Conductors rated at 60 degrees C ?
I intrepret 3605.4.1 to mean that where the temperature rating on the termination of the device is 60 degrees or less, you need to use the 60 degree (first column) of Table E3605.1 (allowable ampacities).

Sooooo....going back to my first post, because in the question it states that the terminals are rated for 60 degrees C, I used the first column (60 degrees C) of Table 3605.1. Because there is no rating for 15 Amps in the 60 degrees column, I went to the next highest rating which was 20amps. 20 amps corresponds with 14 AWG (answer A).

It seems your approach and mine gets the correct answer. But am I applying E3605.4.1 correctly? The answer ICC provided uses the 90 degree column in Table E3605.1 which is allowed by E3605.5.5.

Thus, again brings me back to, "When do you apply E3605.4.1 Conductors rated at 60 degrees C"? To me in my first post, the 90 degree column doesn't apply because the terminals are rated 60 degrees.

Did I just confuse everything again?