Which of these sentences uses commas correctly? a. the president’s chief spokesman, who plans to take a job in the private sector, was often on national television. b. the president’s chief spokesman who plans to take a job in the private sector was often on national television. c. the president’s chief spokesman, who plans to take a job in the private sector was often on national television. d. the president’s chief spokesman who plans to take a job, in the private sector, was often on national television.