ATPL - Which of the following statements about a Mach trimmer is correct?

Question id 383 - Principles of Flight - ATPL - Airline Transport Pilot license

A straight wing aeroplane always needs a Mach trimmer for flying at Mach numbers close to MMO

A Mach trimmer corrects the change in stick force stability of a swept wing aeroplane above a certain Mach number

The Mach trimmer corrects the natural tendency of a swept wing aeroplane to pitch-up

A Mach trimmer reduces the stick force stability of a straight wing aeroplane to zero at high Mach numbers