The average compressive strength of a burnt clay brick is less than 12.5 N/mm2. The allowable rating of efflorescence is:

The average compressive strength of a burnt clay brick is less than 12

1.	The average compressive strength of a burnt clay brick is less than 12.5 N/mm2. The allowable rating of efflorescence is:
A.	Moderate
B.	Serious
C.	Heavy
D.	Zero
Answer» B. Serious