Taxonomy is the scientific field that deals with the classification of organisms. It involves organizing and categorizing organisms based on their shared characteristics and evolutionary relationships. Option 1, morphology, refers to the study of the physical form and structure of organisms, which is one aspect considered in taxonomy. Similarly, option 2, anatomy, focuses on the internal structure of organisms, which is also important in taxonomy. Option 4, economic uses, is not directly related to taxonomy, as it pertains to the practical applications of organisms for human benefit. Therefore, option 3, classification, is the correct answer as it specifically refers to the central focus of taxonomy, which is the systematic arrangement of organisms into different groups based on similarities and differences.