In Each of the Sets Below, Choose the One Quantity

In each of the sets below, choose the one quantity or number which is exact.
A) i. the human population
ii. the distance in light years from the sun to Alpha Centauri, a nearby star
iii. the winning time for the 100 m dash in the Olympic Games
B) i. the weight of a particular one cent coin in g
ii. the boiling point of lead, in °C
iii. the number of cm in 1 yd
C) i. the measured value of the speed of light (2.998 × 10⁸ m/s)
ii. π (3.141)
iii. the volume of milk in a 1-gallon jug