Consider A is a set and B is another set, if Au B=A n B, then Select one:
A = B
A = Null
A = U
B = Null​

A = B

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Core exercises train the muscles in your , lower back, pelvis hips and abdomen  so they can work in harmony. and gives you better balance and stability whether your playing outside or climbing a mountain and  most sports and other physical activities depend on stable core muscles.

Explanation: