Step 1: Understanding the stages of moral development.
The stages of moral development are generally arranged from the most basic instincts to higher levels of moral reasoning.
- Level of Instinct (B) is the lowest stage, where moral decisions are based on biological impulses and instincts.
- Level of Custom (A) involves the adherence to societal norms and customs.
- Level of Reflection (C) is when individuals begin to reflect on and analyze their moral decisions.
- Level of Cultural Relativism (D) is the highest stage, where one understands that moral standards vary across different cultures and is open to multiple perspectives.
Step 2: Conclusion.
The correct order is B, A, C, D.
Final Answer:
\[
\boxed{\text{The correct answer is 3. B, A, C, D.}}
\]