default option 是在不完全契约领域的外文文献经常遇到的一个短语，这个短语在文中到底什么意思？默认选择？貌似不太说得通啊，行家来解释下。。。例句如下，

assuming the initial contract can specify a default option in case renegotiation fails or is unnecessary

As a consequence, no trade is the only possible default option for renegotiation.