Which of the Following Behaviors on the Part of Mother

Multiple Choice

Which of the following behaviors on the part of mother rats lead to an increased resistance to stress later in life in the pups?​ 

A) Increased licking and grooming of the pups by the mothers. 
B) More access to nursing time for the pups. 
C) Nudging the rat pups to play with their siblings. 
D) Providing more solid food at an earlier age.