Which sentence uses commas correctly? The new teacher, who had been at the school only two days, knew the name of each of her students. The new teacher who had been, at the school, only two days, knew the name of each of her students. The new teacher, who had been at the school only two days, knew the name, of each of her students. The new teacher who had been at the school only two days, knew the name of each of her students.