Which word from the paragraph best helps the reader understand the meaning of the underlined word?

The man found out the hard way that it pays to be courteous to the staff at the cafe. He was rude when he complained about not having enough ice in his water. So, his next glass was so full of ice he could scarcely drink it. He remembered to be kind when asking for something after that.  A.full  B.hard  C.enough  D.kind