Which memory strategy is being used when a long number is memorized by breaking it into manageable subunits each containing three digits?

According to the chapter Some Like It Hotabout personality and situational predictors of aggression, the

number and quality of social relationships a person has is known as: (a) social inclusion (b) mate value (c) self-esteem (d) narcissism

Heritability estimates range from 0.00 to ________

Fill in the blanks with correct word