In a kilometre race, A, B and C are three participants. A can give B start of 50 m and C a start of 69 m. The start which B can allow C, is -

Answer: Option D

A : B : C
= 1000 : (1000 - 50) : (1000 - 69)
= 1000 : 950 : 931
In a 950 m race, B can give C a start of
(950 - 931) m
= 19 m
In a 1000 m race, B can give C a start of
= $$\left(\frac{19}{950}\times 1000\right)$$
= 20 m