if you don't mind that the users can see your variables (if so encrypt them), you can pass them over the address. try something like this:
script B:
....
echo "<a href=\"scriptC.php?var1=".$var1."&var2=".$var2."&var3=".$var3."\">click here</a>";
.....
script C:
$var1 = $HTTP_GET_VARS["var1"];
$var2 = $HTTP_GET_VARS["var2"];
$var3 = $HTTP_GET_VARS["var3"];
Michael aka Unique