What does it mean by null in programming?

In computer programming, null is both a value and a pointer. Null is a built-in constant that has a value of zero. It is the same as the character \0 used to terminate strings in C. Null can also be the value of a pointer, which is the same as zero unless the CPU supports a special bit pattern for a null pointer.

Ithink it’s c. 1 pm and 3 pm

Answer (b) the meter will display a negative sign;