Mach tuck is:

A nose-up pitching tendency at high Mach

Yawing at high Mach

A nose-down pitching tendency caused by aft movement of the center of pressure and change in downwash at the tail

Correct

Roll instability at high Mach

Explanation

At high Mach, the center of pressure moves aft and shock-induced changes in downwash reduce tail effectiveness, causing nose-down pitch (tuck).

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