Question

what instruction must always come from a swim coach or other expert swimmer?
how to improve muscular strength.
how to create shapes with the arms.
how to time breathing and swimming.
how to increase flexibility.

Explanation:

Timing breathing and swimming is crucial in swimming and requires expert - level knowledge to teach correctly. Improving muscular strength, creating arm shapes, and increasing flexibility are more general fitness or body - movement aspects not as uniquely tied to swimming expertise as breathing and swimming timing.

Answer:

How to time breathing and swimming.