Question

The little boy asked why don't you wear a shirt gamdhiji

Answer 1

Gandhi ji just weared cloths that were sewed by charkha . the boy was not aware of that and hence the boy asked the little boy why don't you were shirt

Answer 2

Gandhiji was probably in Britain when this question was asked.
Gandhiji wore only a white dhoti and a small upper garment made by charkha. Seeing him shirtless in Britain the boy might have been puzzled as such trends were not prevalent there.