In the following question, two statements are given with some words in bold. Which of the following pairs of bold words must be interchanged to make both the sentences grammatically correct.

a. Although nonverbal (A)complications are an important source of (B)information about others’ emotions in all cultures, the (C)extent to which they are used to infer others’ feelings (D)varies across cultures.

b. Without (E)adequate vitamin intake, you may feel (F)lethargic, be vulnerable to infection and develop other serious (G)cues that can (H)endanger your health and life.