The correct answer is option 2: Ants. Myrmecology is the scientific study of ants. It focuses on various aspects of ants` biology, behavior, ecology, and classification. Ants are social insects and have a complex social structure, making them an interesting subject of study in the field of biology. Myrmecologists observe and analyze ant colonies to understand their communication systems, foraging patterns, reproduction, and interactions with other species. They also investigate the role of ants in ecosystems, such as their impact on plant pollination and seed dispersal. While insects, crustaceans, and arthropods are related groups, myrmecology specifically focuses on the study of ants and does not encompass the other options mentioned.