As a boy,he was found ()hard all day long.

A 发现他被强迫（made）努力劳动(to work hard).
B不对,因为按照b的句型的意思是：被发现他逼别人努力工作,但是必须加一个谓语在was found to make ______ work hard,逼谁努力工作,b里面少了这个东西,所以错了