We do not see the blood vessels and neurons that lie in front of the retina because
a. the visual system does not respond much to stimuli that never change.
b. these structures are made of special proteins whose fibers make them transparent.
c. they are blocked by the vitreous humor.
d. they lie behind the lens and cornea.
Question 2
Abnormalities in muscle fiber proteins characterize
a. myasthenia gravis.
b. muscular dystrophy.
c. Parkinson's disease.
d. Huntington's disease.
