$13.$ Select the BEST implication of the following statement: $90$ percent of a manufacturer$$s profit comes from repeat purchases: only $10$ percent comes from trial or sporadic purchases.$$ Therefore: $\_\_\_\_\_\_\_\_$

a$.$ companies should work harder to find new customers b$.$ existing customer retention is a given, focus all of your energy on finding new customers c$.$ a company$$s first market should always be its current customers d$.$ consider launching new brands to attract new customers