How to check if tablerate is active in custom shipping method?

Which one of the five is least like the other four? Pen—Ink—Pencil—Paintbrush—Ballpoint Cauliflower—Courgette—Carrot—Fennel—Potato Knee—Arm—Hair—Head—Foot Ship—Plane—Helicopter—Hang-glider—Balloon Eagle—Falcon—Vulture—Hawk—Cormorant Bricks—Roof—Window—Chimney—Wall Carbon—Nitrogen—Oxygen—Sulphur—Tin Knife—Fork—Spoon—Spatula—Saucepan Whale—Dolphin—Seal—Shark—Porpoise Mushroom—Chicken—Carrot—Potato  Solution: […]

Prerequisites:  Pointers in C Functions in C Passing the pointers to the function means the memory location of the variables is passed […]