Tom asked the candy maker if they could make the chocoalte easier_____ into small pieces.

……they could makethe chocolate easier to break into small pieces.
可以这样理
Itis easier for the chocolate to break into small pieces.
（it 是形式主语；the chocolate和to break into small pieces是主动的主谓关系,the chocolate 是逻辑主语）
可变成：
The chocolate is easier to break into small pieces.
（the chocolate 取代了形式主语it）
……they could makeiteasier for the chocolate to break into small pieces.
(it 是形式宾语,easier 是宾补足语, for the chocolate to break into small pieces是真正宾语）
可变成题中出现的句子：
……they could makethe chocolate easier to break into small pieces.
（the chocolate取代了形式宾语it,成为make的宾语,后面to break into small pieces保持不变）
上面所有句子和结构中都需要使用不定式,所以题目答案应该选to break.
理解这个题目,最简单的句子是：
It is easy to learn English./I find it easy to learn English.
可以转化成：
English is easy to learn./I find English easy to learn.