How many full-length strands of hair are collected from the scalp to use as a sample?
2
15
25
50

I think the correct answer from the choices listed above is the last option. It would be 50  full-length strands of hair are collected from the scalp to use as a sample. The more sample the better because you can easily repeat an experiment if there are errors found. Hope this answers the question.

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.