In Python, the '+' operator can be used with numbers and with strings. What is a property that number addition has, but string concatenation does not?
Select one:
a. Numeric addition is allowed on the right-hand side of an assignment statement.
b. More than one numeric addition per expression is allowed.
c. The expression value does not depend on the order of numeric addition operands.
d. Numeric addition is fast to execute.
e. Numeric addition needs 2 operands.