What Is a Common Problem with Students Using Underlining or Highlighting

What is a common problem with students using underlining or highlighting that teachers should be aware of?

A) Students are over-selective and do not highlight or underline enough.
B) Underlining and highlighting are used more than other strategies.
C) Students are under-selective and highlight or underline too much.
D) Underlining and highlighting are only used when studying from textbooks.