If a flexible loop of irregular shape carrying current is placed in a magnetic field.

Why its shape becomes circular?

Why any loop tries to maximize flux when it is placed in magneticfield?

According to me, by changing to circular shape the current carrying loop is maximizing it`s magnetic moment which then minimize it`s potential energy I.e., -M.B the higher the M more negative is the potential energy more is the stability. This reason can be wrong. So don`t rely on it completely.