应该选A,具体的辨析如下：
ENSURE,
INSURE
and ASSURE are
interchangeable in many contexts where they indicate the making certain or
inevitable of an outcome, but ENSURE may
imply a virtual guarantee <the government has ensured the safety of
the refugees>, while INSURE
sometimes stresses the taking of necessary measures beforehand <careful
planning should insure the success of the party>, and ASSURE
distinctively implies the removal of doubt and suspense from a person's mind
<I assure you that no harm will be done>.
大意是ensure经常保证的是一种虚拟的非实物的东西，比如安全什么的；insure一般是通过提前采取一些必要的措施来达到保证的目的；assure特指扫除某人的疑虑或疑问这一类范畴。
希望对你有用。
追问回答错误╮(╯﹏╰）╭
追答哦，不好意思，刚没有看仔细后面的不定式结构，应该是C，词典中的例句：That kind of behaviour is guaranteed to make him angry。
追问不定式作宾语就一定要用guarantee么？
追答词典上的例句是这样的的。