1. **State the problem:** We have the inequality $3.5c - 1.5d \geq 50$ where $c$ is the number of cupcakes sold and $d$ is the number of donuts sold. 2. **Given:** $d = 200$ donuts sold. 3. **Substitute $d$ into the inequality:** $$3.5c - 1.5(200) \geq 50$$ 4. **Simplify the expression:** $$3.5c - 300 \geq 50$$ 5. **Add 300 to both sides to isolate terms with $c$:** $$3.5c \geq 50 + 300$$ $$3.5c \geq 350$$ 6. **Divide both sides by 3.5 to solve for $c$:** $$c \geq \frac{350}{3.5}$$ $$c \geq 100$$ 7. **Interpretation:** Esa must have sold at least 100 cupcakes to satisfy the inequality. **Final answer:** 100 cupcakes (Option C)