Help pls:( Which situation describes parasitism?

Parasitism is where a parasite lives on some living beings and proceed to take their advantage.

Example

A parasite controls a bug's body. This is classified as a Parasitism.

A parasite sucks blood. This is also classified as a Parasitism.

Parasitism is basically one living gets the advantage while the another living gets disadvantage.

From the choice, the answer is C because the ticks live on the cow and suck their blood, giving the cow disadvantage. The cow will slowly die and if the cow dies, the ticks will find a new one or die if they don't find any livings to live on.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.