Correct Answer - A Ans. is 'a' i.e.,Fourth ventricle [Ref Med | Anatomy embryology histology videos & books

Correct Answer - A
Ans. is 'a' i.e.,Fourth ventricle [Ref Medical Dictionary, 2009
Farlex and Partners]

It is a shallow depression, of a blue color in the fresh brain,
lying laterally in the most rostral portion of the rhomboidal
fossa near the cerebral aqueduct; it lies near the lateral wall of
the fourth ventricle and consists of about 20,000 melaninpigmented neuronal cell bodies the norepinephrine-containing
axons of which have a remarkably wide distribution in the
cerebellum as well as in the hypothalamus and cerebral cortex.
Also called as locus cinereus, locus ferrugineus.

@anatomyvideoss