The correct answer is A. Algae.
Phycology is the branch of botany that deals with the study of algae. Algae are a diverse group of photosynthetic organisms that are found in both aquatic and terrestrial environments. They are a major component of the marine food web and play an important role in the cycling of nutrients. Algae are also a source of food, fuel, and pharmaceuticals.
Fungi are a separate kingdom of organisms that are not plants. They are eukaryotic, meaning that their cells have a nucleus, but they do not have chlorophyll and are therefore not photosynthetic. Fungi are found in a variety of habitats, including soil, water, and on living and dead organisms. They play an important role in the decomposition of organic matter and the cycling of nutrients.
Ecology is the study of the relationships between organisms and their environment. It is a broad field that encompasses the study of populations, communities, ecosystems, and the biosphere.
Viruses are not living organisms. They are non-cellular particles that can replicate only within living cells. Viruses are responsible for a variety of diseases, including the common cold, influenza, and AIDS.