【单选题】听力原文: (27[D])Two rail companies were fined a total of £325,000 yesterday for 'an unsafe system of work practices' that led to the death of a 22-year-old student. Michael Mungovan, studying at Brunel U...
A.
Because they asked young students to work at night.
B.
Because their train was not safe.
C.
Because they hired college students illegally.
D.
Because their work practice system was unsafe.