Which plasma protein is responsible for transporting metal ions in the blood?

the dark variety, as they are not visible on the dark tree barks

explanation:

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