To get to work Kate must drive for 10 minutes to reach Newtown Station, take the next train to Central Station in the city and then walk for 20 minutes to reach her office. Whenever Kate arrives at Central Station later than usual, she takes a taxi from there to her office. The taxi takes 5 minutes to make the journey. Trains to Central Station depart every 30 minutes and Kate always plans to arrive at Newtown Station 20 minutes before her train is due to depart. This morning Kate arrived at work 15 minutes later than usual.

Which of the following would explain why Kate arrived at work 15 minutes later than usual?

A) The train that Kate normally takes was 20 minutes late

B) Kate arrived at Newtown Station 15 minutes later than usual

C) Kate arrived at Newtown Station 45 minutes later than usual

D) The train that Kate normally takes was 15 minutes late