The answer is b. nematocyst. (hope this helps!)
<span>Microtubules form from dimers of Alpha and Beta subunits that polymerize into a hollow tube. Alpha and beta subunits refer to tubulin. There are things that can stop this from happening, and when one of these events occurs, de-polymerization is called "catastrophe".</span>
Sterilization is the process that kills all microbes by the use of physical/chemical agents.
Essential amino acids are amino acids that must be supplied to one's body by their diet because they cannot be synthesized from scratch.