What is the MOST effective way for Marie to combine sentences 4 and 5?

Responses
A If the producer has a product or service that many consumers want to purchase, or they can charge more for the product or service.If the producer has a product or service that many consumers want to purchase, or they can charge more for the product or service.
B If the producer has a product or service that many consumers want to purchase they can charge more for the product or service.If the producer has a product or service that many consumers want to purchase they can charge more for the product or service.
C If the producer has a product or service that many consumers want to purchase, they can charge more for the product or service.If the producer has a product or service that many consumers want to purchase, they can charge more for the product or service.
D If the producer has a product or service that many consumers want to purchase, but they can charge more for the product or service.

C If the producer has a product or service that many consumers want to purchase, they can charge more for the product or service.

The most effective way for Marie to combine sentences 4 and 5 is option C: If the producer has a product or service that many consumers want to purchase, they can charge more for the product or service.