Question

the human body contains as many as 1 ______ neurons.

○ trillion
○ hundred thousand
○ million
○ billion

Explanation:

In biological knowledge, the human body's nervous system contains a very large number of neurons. The correct estimate for the number of neurons in the human body is around 1 trillion. The other options (hundred thousand, million, billion) are too small to represent the actual quantity of neurons.

Answer:

A. trillion