Which One of the Following Statements About Literature Reviews Is

Which one of the following statements about literature reviews is correct?

A) Literature reviews must cite a range of different sources - from historical literature to contemporary studies.
B) Every literature review must cite sources published within the past couple of years of the review writing.
C) Including contradictory research findings makes the literature review look weak and unclear.
D) If previous studies produced findings unfavorable to the researchers' point, these findings should be included.