By the ABC model, _________________.a. Antecedents trigger Behavior that has Consequencesb. three master gene sets $(A,B,C)$ control flower formationc. gene $A$ affects gene $B$, which affects gene $C$d. both b and c

Key Concepts: Abc Model Explanation: The ABC model states that antecedents trigger behavior that has consequences. Step by Step Solution: Step 1. Option a describes the ABC model correctly, as antecedents trigger behavior that has consequences. Step 2. Option b is incorrect as it describes the three master gene sets that control flower formation, not the ABC model. Step 3. Option c is also incorrect as it describes the relationship between gene A, B, and C, not the ABC model. Step 4. Therefore, the correct answer is option a. Option d is incorrect since it includes options b and c which are both incorrect. Final Answer: a