John used to work as a tool and dye maker. Before that he was employed as a truck driver. However, due to the recession, he has been out of work for two years and is now training to be a carpenter. John has a high school diploma and some post$-$high school training in the skilled trades. John most likely belongs to the:

a$)$ working class

b$)$ lower middle class

c$)$ upper middle class

d$)$ working poor