Which of the Following Best Defines Sensitive Period

Which of the following best defines sensitive period?

A) A time of psychological fragility, usually due to some type of loss such as the death of a spouse, termination of employment, deterioration due to aging, etc.
B) The period of time during which developmental norms for physical development are reached or achieved.
C) A specific period in development when an organism is particularly responsive to specific forms of experience or particularly influenced by their absence.
D) The time when the tension between nature and nurture is resolved in an organism's development.