If the Following Pseudocode Were an Actual Program,what Would It

Multiple Choice

If the following pseudocode were an actual program,what would it display?
Declare String str = "a1b2c3d4"
Declare Integer index
Declare Integer num = 0
For index = 0 To length(str) - 1
If isDigit(str[index]) Then
Set num = num + 1
End If
End For
Display num

A) 3
B) 0
C) 5
D) 4
E) None of the above.