A car is moving collinearly with a laser beam emitted by a transceiver. A laser pulse emitted at $t=0 \; \text{s}$ is received back by the transceiver $100 \; \text{ns}$ (nanoseconds) later after reflection from the car. A second pulse emitted at $t=0.1 \; \text{s}$ is received back $90 \; \text{ns}$ later. Given the speed of light is $3 \times 10^{8} \; \text{m/s},$ the average speed of the car in this interval is _________
- $54 \; \text{kmph,}$ moving towards the transceiver
- $108 \; \text{kmph,}$ moving towards the transceiver
- $54 \; \text{kmph,}$ moving away from the transceiver
- $108 \; \text{kmph,}$ moving away from the transceiver