I would say grassland. I would say so because if you look at the options you can tell that arctic isn´t right because it´s ice and snow, tropical rain forest isn´t right because a RAIN forest gets lots a RAIN hint hint, and a desert, that does´nt set any kind of rain, but its sand not soil. For 4 its makes sense because during the summer there can be rain but little rain at little rain at all.
Hope I helped!
