how could scientists test the hypothesis of different areas having lighter or dark skin pigmentation ​

scientists can test differences of the area with pigmentation by observing which is lighter and which is darker however they use microscope to look the difference of the pigmentation over the cells.

b brown mice / white sand dunes

endo:

regulates body hormones, aldosterone, vasopressin

neural:

signal, regulates body using electric signals, reflex

endo has to do with hormones; aldosterone and vasopressin are both hormones. i also had this question and got it right : d