I am working on magento 1.9.1.
I am offering free shipping if customer chooses a product from particular category (Say Category B).
In the cart page, the customer have added other category products too.
Product 1 - Category A, Product 2 - Category C, Product 3 - Category B
Now, the coupon must not apply if Other category products are added (Say Category A & C).
Is there a method for this to happen?