CompTIA Exam Questions

Which of the following is this an example of?

After Matt, a user, enters his username and password at the login screen of a web enabled portal,
the following appears on his screen:
‘Please only use letters and numbers on these fields’
Which of the following is this an example of?

A.
Proper error handling

B.
Proper input validation

C.
Improper input validation

D.
Improper error handling