DrDieringer Wants to Study Attachment Patterns in Single-Parent Families

Dr.Dieringer wants to study attachment patterns in single-parent families.She plans to define the strength of attachment as the time it takes for the parent to respond when the infant starts to cry.Why is this operational definition important

A)  It allows others to understand exactly what Dr. Dieringer means by "attachment." 
B)  It allows Dr. Dieringer to generate a scientific hypothesis. 
C)  It prevents research assistants from violating ethical guidelines for psychological research. 
D)  It requires a double-blind research design.