As per the given description, the neurotransmitter that is likely to be in short supply for Junita is Serotonin as it controls the mood of human beings along with the behavior and mood. It also regulates sleep and memory in human beings. Junita might have been carrying low levels of 'serotonin' in her blood that has led a depressed and sleepy mood with the loss of appetite. Thus, 'serotonin' is the neurotransmitter that is in short supply for Junita and left her with a depressing mood. Therefore, <u>option B</u> is the correct answer.
