Which of the following is the NRC rating that indicates a complete absorption of sound?

A.
0

B.
1

C.
99

D.
100

E.
1000

Explanation:
A noise-reduction coefficient (NRC) rating of 1 indicates a complete absorption of sound. NRC ratings are used
to indicate the relative amount of sound energy that can be absorbed by acoustic paneling, carpeting, tile, and
other sound-absorbing materials. The higher the NRC rating, the greater the level of sound absorption. Cisco
recommends using acoustic panels with an NRC rating of 0.75 or greater.
An NRC rating of 0 indicates no sound absorption. Only NRC values from 0 to 1 are used; NRC values below 0
or above 1 are not valid.

Cisco: Cisco TelePresence Room Design Guide: Noise-Reduction Coefficient (PDF)