A drug A & B compared, all are true except____________?

A. 1 mg of A causes same effect of 3 mg of B, so A is more potent
B. 1 mg of A cause effect not even caused by maximum tolerated dose of B, so drug A is more efficacious
C. 1 mg of A cause effect not caused by 1 mg of B so A is more efficacious
D. Efficacy is not dose dependent