Glen was a bit grumpy. He just found out from a coworker that one of his peers, someone who was hired for the same job as him at about the same time, made more money than him. He was really mad and was trying to decide what to do about it$.$ According to equity theory, which of the following are possible things he can do to restore equity$/$fairness$?$O a$.$ Quit his job b$.$ Ask his boss for a raise O c$.$ Work less hard d$.$ All of the above