Concept:A population refers to individuals of the same species occupying a particular area at the same time.Explanation:To identify a population, all the members must belong to the same species.They must also live together in a specific habitat or geographical area.For example, all the tilapia fish in a pond form a population.Therefore, a group containing different species or a mix of plants and animals cannot be called a population.Answer:A. A group of the same species of organisms living together