问题详情

We learn from the third paragraph that().
A．London was plagued with rats in the 1 950s.
B．London is covered with smog today.
C．London was polluted by smog in the 1 950s.
D．Los Angeles is as heavily polluted today as London was in the 1 950s.请帮忙给出正确答案和分析，谢谢！