Final answer:
Coral is a modular organism because it grows in colonies with repeating units that can become new colonies.
Step-by-step explanation:
Among the options provided, coral represents a modular organism. Modular organisms are those that are made up of repeating units, often capable of living independently if separated from the main body. Corals grow in colonies and can reproduce asexually to create copies of themselves, which can then grow into new colonies.
Lizards, dogs, and ants are considered unitary organisms since they maintain a constant body plan as they grow and do not readily split into independent, viable units.