I really don’t know how_________ with the rest of the food.

A. to do B. to deal C. doing D. dealing

B

句意：我真地不知道如何处理剩下的食物。考查动词短语和动词不定式。特殊疑问句How+to do sth.：怎样做某事，故排除C和D；deal with和do with意思是：应付，对付，处理，deal是非及物动词，怎样处理某事是how to deal with sth.，do是及物动词，怎样处理某事是what to do with sth.；根据句意和“how”可知选B。