Final answer:
The quantity representing velocity from the given options is B. 65 m/s east, as it includes both a speed and a direction, which are the required components of velocity.
Step-by-step explanation:
The quantity that represents velocity must have both magnitude and direction. Therefore, from the provided options, the one that includes both magnitude and a specific direction would be the correct answer for representing velocity. The options include:
- A. 150 km: This is only a distance, with no direction specified, so it's not a velocity.
- B. 65 m/s east: This has both a magnitude (65 m/s) and a direction (east), which makes it a velocity.
- C. 12 km/h: This is only a speed, as there is no direction mentioned.
- D. 78 cm: This is just a length, not a velocity.
- E. 34 cm/min to the left: Although this has both a magnitude and direction, it is not presented as one of the primary options.
Therefore, the correct answer is B. 65 m/s east, as it correctly constitutes a velocity with both magnitude and direction.