Final answer:
The best way to promote a business online is c)to advertise your company's product.
Step-by-step explanation:
The best way to promote a business online is to advertise your company's product. While offering helpful and free information can be a good strategy for building brand credibility, and collecting information can assist in market research, the ultimate goal of promoting a business online is to generate sales and increase brand visibility. By advertising your company's product, you can reach a wider audience and attract potential customers.