45. In a lecture, a professor named a molecule 2-ethyl-4-tertiary-butylpentane. A student pointed out that although the correct structure could be drawn from this name, the name did not follow systematic rules. Which of the following is the correct systematic name for the molecule? (A) 2-t-butyl-5-methylhexane (B) 2-ethyl-4,5,5-trimethylhexane (C) 3,5,6,6-tetramethylheptane (D) 2,2,3,5-tetramethylheptane