Which is NOT mentioned as a cause of American students' casual writing

A．parallels a social tendency of being informal
B．worries students as well as professors
C．is taken as trivial by employers
D．is ignored in all business concerned sciences

A．More and more students ask her to teach how to write instant messages.
B．More and more structural errors are seen in her student's writings.
C．Students are becoming increasingly indifferent to learning English.
D．Parents are more demanding as to the teaching content of the school.