Four Commuter Trains and Two Express Buses Depart from City

Multiple Choice

Four commuter trains and two express buses depart from city A to city B in the morning, and three commuter trains and three express buses operate on the return trip in the evening. In how many ways can a commuter from city A to city B complete a daily round trip via bus and/or train? ​

A) 23 possible ways
B) 11 possible ways
C) 36 possible ways
D) 18 possible ways
E) 60 possible ways
F) 63 possible ways