In human anatomy, the term central nervous system refers to which main parts of the nervous system?

Introduction / Context:
Biology and general science questions often ask about basic structures in the human body. The nervous system is commonly divided into central and peripheral parts. This question checks whether the learner knows which organs form the central nervous system, a fundamental point needed for understanding reflexes, sensations and voluntary movements.

Given Data / Assumptions:
- The term central nervous system is mentioned in the question.
- The options list different combinations of brain, spinal cord, cranial nerves and peripheral components.
- We assume the candidate has studied simple diagrams of the nervous system in school level science textbooks.

Concept / Approach:
The central nervous system, usually abbreviated as CNS, consists of the brain and the spinal cord. These serve as the main control centres, receiving information from sense organs, processing it and sending commands to muscles and glands. The rest of the nerves throughout the body form the peripheral nervous system, which connects organs and limbs to the CNS. Cranial nerves, although they arise from the brain, are grouped under the peripheral nervous system in most standard classifications.

Step-by-Step Solution:
Step 1: Recall the textbook definition of the central nervous system as the combination of the brain and spinal cord. Step 2: Note that cranial nerves and spinal nerves which branch out to various body parts are usually listed as part of the peripheral nervous system, not the central one. Step 3: Examine the options and select the one that includes only the brain and spinal cord without adding cranial nerves or other systems. Step 4: Confirm that the option stating brain and spinal cord exactly matches the standard definition of the central nervous system.

Verification / Alternative check:
A quick mental image of a simple diagram in biology texts shows the central nervous system as a vertical axis comprising the brain in the skull and the spinal cord running through the vertebral column. Every other nerve is drawn as branching away from this axis and is discussed under the peripheral nervous system. This visual memory helps verify that the CNS is limited to the brain and spinal cord.

Why Other Options Are Wrong:
Autonomic and peripheral nervous systems: These are functional and structural subdivisions that are mainly part of the peripheral nervous system, not the central one.
Brain and cranial nerves: Cranial nerves are peripheral nerves that arise from the brain, so this combination does not represent the central nervous system as defined in textbooks.
Brain, spinal cord and cranial nerves: Adding cranial nerves extends beyond the strict definition of the central nervous system and mixes central and peripheral components.

Common Pitfalls:
Students often assume that anything connected directly to the brain must be central, so they incorrectly include cranial nerves. Others confuse functional subdivisions like autonomic nerves with structural subdivisions. The key is to remember that the central nervous system is defined strictly by location inside the skull and vertebral canal, which includes only the brain and spinal cord.

Final Answer:
The central nervous system consists of the brain and spinal cord.