As compared to a routine case control study, nested case control study avoids problems (in study design) related to -: (A) Temporal association, (B) Confounding bias, (C) Need for long follow up, (D) Randomization
Answer is A. A nested case-control (NCC) study is a variation of a case-control study in which cases and controls are drawn from the population in a fully enumerated coho. Usually, the exposure of interest is only measured among the cases and the selected controls. Thus the nested case-control study is more efficient than the full coho design.