A program that is said to have referential transparency possesses what property?

Question $40$ options:

$1)$

any two expressions that have the same value can be substituted for each other but there may be an effect on the actions of the program

$2)$

any two expressions that have the same value can be substituted for each other with no effect on the actions of the program

$3)$

all references to variables must be traced back to a memory location holding the value of that variable

$4)$

all references to variables are visible and public to all programmers using that language