If two organisms are in the same class, they must also be in the same

phylum & kingdom

Explanation:

if two organisms are in the same ORDER, they must be in the same class, phylum & kingdom. even though the cat & the housefly have the same species group name (domestica), they CAN'T BE the same species because they are not in the same genus, family, order, etc.

a. decomposes use carbon from dead organisms as fuel for cellular respiration, returning carbon dioxide back into the atmosphere.

the answer is d. chordata