What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_7, x_7 will listen to a song or x_7 is not sad. For all x_7, x_7 will listen to a song if and only if x_7 is a musician.
For all x_7, if x_7 were sad, then x_7 is listening to a song. For all x_7, if x_7 listens to a song, then x_7 is a musician. For all x_7, if x_7 were a musician, then x_7 is listening to a song.