Which of the following would NOT lead to increased pigmentation?

A. he could develop brittle bones
Brittle bones are more associated with osteoporosis or osteogenesis imperfecta, not primarily from vitamin D deficiency due to lack of sunlight.

B. he could develop very dense bones
Dense bones are seen in conditions like osteopetrosis, which results from defective osteoclast activity-not lack of sunlight.

C. he could develop soft, bowed bones
Lack of sunlight leads to vitamin D deficiency, impairing calcium absorption, which causes rickets in children and osteomalacia in adults, both of which involve soft, weakened bones that may bow under body weight.

D. he could develop nightmares
While isolation might impact mental health, this has no direct link to skeletal effects or bone physiology.

A. axon
The axon transmits signals away from the neuron’s cell body toward other cells. Blocking it would prevent output, not input.

B. dendrite
Dendrites receive input from other neurons. Blocking dendrites would prevent the neuron from receiving synaptic signals.

C. synapse
The synapse is the junction between neurons. While blocking the synapse can prevent transmission, the question specifies receiving input, which happens at the dendrites.

D. synaptic cleft
This is the small gap between neurons where neurotransmitters are released. Blocking it affects signal transmission but not specifically the receiving end, which is the dendrite.