Fussy / Picky Eater

Hi. My 3 years old girl has just started nursery school. The teacher comments that she doesn't want to eat dishes such as vegetables, meats, etc.. only eat want eat plain rice. She is also doing the same at home. Only eats plain rice and noodles. She doesn't like to eat dishes. Any parents facing some issues with the toddlers? Why do they behave like that?