"On the whole," Ms. Dennis remarked, "engineering students are lazier now than they used to be. I know because fewer and fewer of my students regularly do the work they are assigned."

The conclusion drawn above depends on which of the following assumptions?

(A) Engineering students are working less because, in a booming market, they are spending more and more time investigating different job opportunities.
(B) Whether or not students do the work they are assigned is a good indication of how lazy they are.
(C) Engineering students should work harder than students in less demanding fields.
(D) Ms. Dennis' students are doing less work because Ms. Dennis is not as effective a teacher as she once was.
(E) Laziness is something most people do not outgrow.