(A) Lyophilic colloids such as starch, gelatin, etc, act as protective colloids .
(R) Protective power of lyophilic colloids is expressed in terms of gold number.
A. IF both (A) and (r) are correct and (r) is the correct explanation for (a).
B. If both (a) and (r) are correct but (r) is not the correct explanation for (a).
C. IF (a) is correct but (r) is incorrect.
D. If (a) is incorrect but (r) is correct.