A. Constant variables need not be defined as they are declared and can be defined later
B. Global constant variables are initialized to zero
C. const keyword is used to define constant values
D. You cannot reassign a value to a constant variable

Solution

A. Constant variables need not be defined as they are declared and can be defined later

Explanation

Since the constant variable has to be declared and defined at the same time, not doing it results in an error.