I know rotten is a special kind of bad, but shouldn't also bad mangoes be accepted here? It is common to say that fruits and vegetables have "gone bad" when they are rotten.
Yeah, "mbovu" is closer to "spoiled" than "rotten." You can have a "gari mbovu" - spoiled car.
True. But as it seems, the course still lacks alternative answers. We are limited to what they are giving us.