In accordance with a cellular theory of aging, the process of cross-linking may lead to which of the following vision-related changes?

Sucking, cuddling, looking, smiling, and crying are all infant behaviors that

encourage __________ . Fill in the blanks with correct word

One reason why passionate love has received so much attention from scientists and scholars is because

a. it is the strongest form of friendship b. it is a rare and mystical event c. it appears to be a universal human experience d. it is incredibly easy to study