Cerebrospinal fluid (csf) is an effective barrier against all poisons and drugs has the same chemical composition as blood plasma has more protein and less sodium and chloride ions than blood plasma is formed in the choroid plexuses of all four brain ventricles all of the listed responses are correct.

is formed in the choroid plexuses of all four brain ventricles.

Explanation:

Cerebrospinal fluid is a colorless, clear body fluid which is found in brain and spinal cord.  

It is secreted by some special ependymal cells which are present in choroid plexuses of ventricles of brain, and are absorbed in arachnoid granulations.

It acts as a buffer for brain. It provides basic immunological and mechanical protection to brain which is present inside the skull.

Options that are wrong, there reasons:

(a) is an effective barrier against all poisons and drugs has the same chemical composition as blood plasma.

(b) has more protein and less sodium and chloride ions than blood plasma

Reason - CSF is derived from the blood plasma. It is similar to it except that it is protein-free compared with that of plasma and some electrolytes like sodium chloride.

yes and no depends if she cut her ginger deep