The sympathetic and parasympathetic nervous systems are both part of which division of the nervous system? a. the central nervous system b. the peripheral nervous system c. the somatic nervous system d. the autonomic nervous system

The answer would be D. Autonomic nervous system. 

Here is an outline of the nervous system divisions:

TWO MAIN DIVISIONS:
I. Central nervous system (CNS)
II.Peripheral nervous system (PNS)
       II.A. Somatic Nervous System (SNS) - voluntary movement
       II.B. Autonomic Nervous System (PNS) - involuntary movement
             B1. Sympathetic Nervous system - Fight or fight response)
             B2. Parasympathetic Nervous system - Relaxing and calming

If your question is pertaining to the two main divisions of the nervous system then answer would be peripheral nervous system. But to be more specific, the sympathetic and parasympathetic nervous systems are directly under the AUTONOMIC NERVOUS SYSTEM.