**This question is based on Simpson's Paradox.**

1.Success rate of Dr.B in Stage Ⅲ (49/50 =98%)** > **Success rate of Dr.A in Stage Ⅲ(78/80 = 97.5%)

2.Success rate of Dr.B in Stage Ⅳ (11/50 = 22%) **>** Success rate of Dr.A in Stage Ⅳ(2/20 =10%)

3.The aggregate Success rate of Dr.B (60%)**< **The aggregate Success rate of Dr.A (80%)

I recommend Dr. B because her success rate in both stages Ⅲ and Ⅳ is greater than Dr. A.Individual success rate is matter rather than aggregate.

**Correct ****ans**** is (d)Doctor B since she appears to be more successful**