19. the pia mater layer in the ventricles is rich in blood vessels that produce
a. keratin.
b. csf. c. new skin.
d. dopamine.

Ichoose a as my answer

The virus is considered to be are living item since they have hereditary material dnas or rnas. they can imitate and change. they respond to boosts, for example, radiation, chemicals, and warmth. they have antigenic properties. they are proficient to duplicate with a same hereditary constituent.

The direction a chemical reaction occurs is represented by an arrow