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

a)

Two speakers are playing the same music but you are standing between them so that the waves produced are completely out of phase (they differ by half a wavelength). What is the resulting sound?The sound waves will add and the music will be twice as loud. The sound waves will differ by a time lag and it will sound like an echo. The sound waves will cancel out and there will be no sound where you are standing. You will hear the music as you normally would.\fA wave travels between two ends of a medium such that the reflected wave superimposes with the original wave with the opposite phase creating a wave that looks stationary. A wave travels through a medium that is capable of slowing down the wave to a stop. A wave travels between two fixed-ends of a medium such that the reflected wave superimposes with the original with the opposite phase creating a wave that looks stationary. A wave travels between two ends of a medium such that the reflected wave superimposes with the original at the same phase creating a wave that looks stationary