Please help I have been stuck on these homework question for a long time!!

a)

Which statement(s) about mechanical waves is true?Mechanical waves in rigid materials are slower than in less rigid materials. Mechanical waves in rigid materials travel farther than in less rigid media. Mechanical waves in rigid materials have a higher frequency than those in less rigid materials. Mechanical waves in less rigid materials last longer than in rigid materials.A guitar string is 60 cm long. What is the wavelength of the second harmonic for this string