_______________ is swim on the back in swimming.

Correct option is A

· The swimming stroke where one swims on their back is called the backstroke.
· This stroke is distinct for being performed while lying on the back, allowing swimmers to breathe continuously and maintain a streamlined position.
Details on other options:
· Streamline: This is a position used in all strokes to minimize resistance, characterized by a tight, straight body posture, usually after a start or turn.
· Butterfly stroke: This stroke involves a simultaneous overhand arm movement and a dolphin kick, performed face down in the water.
· Freestyle: This is typically the fastest stroke, where swimmers can use any style, but the front crawl is most commonly used, performed face down in the water.