1. **State the problem:** Simplify the expression $12 - 3 + (-2) - 1$. 2. **Apply the order of operations:** Addition and subtraction are performed from left to right. 3. Calculate step-by-step: $$12 - 3 = 9$$ $$9 + (-2) = 9 - 2 = 7$$ $$7 - 1 = 6$$ 4. **Final answer:** The simplified value of the expression is $6$. This corresponds to option B.