There is a question in our grammar book that goes like this:
Her husband, a plumber's assistant, earns only 300 dollars a month, which makes it very difficult for her to feed and clothe her children properly, ______________ send them to school.
a. much more
b. still more
c. much less
d. even less
The book says that the answer is C. How do i explain it in the clearest way possible to my student? She is an intermediate level.