Answer:
a. $_SESSION
Explanation:
A session variable in PHP can be accessed using the global variable $_SESSION.
This can be used for both setting and retrieving session values as described subsequently.
$_SESSION["var1"] = "value1";
This set a session variable called 'var1' to a value 'value1'. Later if we want to retrieve this value we can do it as follows:
echo "Value of session variable 'var1' is " . $_SESSION["var1"] ;
This will print the result: Value of session variable 'var1' is value1
