When a person is developeing a plan, he must understand the or what he is selling.

marketing

promotion

product

Product

Explanation:

When a person is developing a plan, he must understand the product he is selling.

He can only develop an effective plan if he knows the complete dimensions of the product at hand. An incomplete understanding would lead to developing an ineffective plan that might create the wrong perception of it in the minds of the consumer and eventually effect the sales negatively or maybe engage the wrong market in the process.