As per IS 456-2000, what is the recommended value of effective length of an RCC compression member of unsupported length l that is effectively held in position and restrained against rotation at one end and at the other end restrained against rotation but not held in position?

A) 0.65l

B) 0.7l

C) 0.8l

D) 0.9l

As per Table 19 of IS 456-2000, the effective length of compression members restrained in direction and position at one end and restrained in direction at the other end should be taken as 0.8l. Therefore, option C is the correct answer.