[单选题]
A car decelerates uniformly and comes to a sth t 2v 0+joms1yshv7;lop after 10 s. Tyqbyidv7v9lk;*5.v khe car's average velocity during dece7vd;ybki yvq 9k5 .lv*leration was 50 km/h. What was the car's deceleration while slowing down?
A. 10 km/h/s
B. 5 km/h/s
C. 250 km/h/s
D. 10 km/h/s