{{B}}quEstions 15-18{{/B}}

A、thErE ArE not EquAl numBErs oF mAlEs AnD FEmAlEs.
B、thE sAmplE pool is too smAll.
C、thE quEstionnAirE survEy FAils to inCluDE Enough quEstions.
D、thE stuDEnts DiDn’t givE DEFinitE AnswErs to thE quEstions.