Radical 口
6 strokes
嗎
mouth 口 (5) + horse 马 (44) = question mark 吗
This is a particle which is added to the end of a sentence to turn it into a question.

Imagine looking inside the mouth of a horse you are thinking of buying, and finding a question mark stamped on the horse’s tongue. / Your robot remarks, “It’s not logical to buy horses at this market.”