What are the four common forms of market development strateg

A market development strategy targets non-buying customers in currently targeted segments.It also targets new customers in new segments.
A marketing manager has to think about the following questions before implementing a market development strategy:Is it profitable?Will it require the introduction of new or modified products?Is the customer and channel well enough researched and understood?
The marketing manager uses these four groups to give more focus to the market segment decision:existing customers,competitor customers,non-buying in current segments,new segments.

你是要翻译吧？译文：
在国际环境中市场发展战略的四种基本形式是什么？叙述一下它们的优点和缺点。