Two cars P and Q are moving in a racing track continuously for two hours. Assume that no other vehicles are using the track during this time. The expressions relating the distance travelled $d$ (in km) and time $t$ (in hour) for both vehicles are given as

P: $d=60 \: t$

Q: $d=60 \: t^2$

Within the first one hour, the maximum space headway would be

1. $15$ km at $30$ minutes
2. $15$ km at $15$ minutes
3. $30$ km at $30$ minutes
4. $30$ km at $15$ minutes
in Others
edited