What are Constant/control variables

constant = changes and control is used as the basis of comparison

Explanation:

Constant variables are variables that do not change

e.g such as the temperature ( if it's meant to be kept at a constant temp).

Control variables are meant to be kept constant to allow for a comparison and thus determine the effect of IV (independant variable) and DV ( dependant variable)

well for one plants are always the producer, so a is the answer. a wolf is more of the consumer(predator) and the deer is the prey so i know those two are out of the question. also mushrooms are fungi/fungus so a is the producer.

protistas excret ethanol used in the manufacture of vinegar