The part of the brain closest to the spinal cord is the Blank; it is important for functions such as Blank.

option A - denature

Explanation:

Microbial control agents are KNOWN to DENATURE cell proteins as a step in pathology of many diseases.

And because PROTEINS ACTIVITY depends on their three dimensional configuration, microbe attack and BREAK the bond in order to penetrate the cell membrane.

So, the ONLY right option is A