A tired man has moved through x metres in t minutes. If $\mathrm{x}=80\mathrm{t}-5{\mathrm{t}}^2.$ What is the time elapsed and distance covered, before he comes to rest ?

• A

  10 sec; 350 m

• B

  8 sec; 300 m 

• C

  12 sec; 400 m

• D

  8 sec; 320 m