Three things are necessary for humans to keep their balance while walking on two legs

we are able to balance because of sensory input from vision, touch, and motion. integration of that sensory input and motor output to the eye and body muscles

The correct answer is a. we know this because n (hap) + n (hap) = 2n (dip).

Neurotransmitters are messengers responsible for communication between neurons. they are released from synaptic vesicles and are received by receptors.  the communication is referred to as neurotransmission. the following statement is true about neurotransmitters: a. they're stored in synaptic vesicles in the axon.