ANSWER
[tex]a)1.25\cdot10^1\text{ m/s}[/tex]EXPLANATION
We want to convert the speed of the bus from kilometers per hour to meters per second.
To do this, multiply the speed in km/hr by 1000 and divide by 3600. That is:
[tex]1\text{ km/hr}=\frac{1000}{3600}\text{ m/s}[/tex]Therefore, we have that 45 km/hr is:
[tex]\begin{gathered} \frac{45\cdot1000}{3600} \\ \Rightarrow12.5\text{ m/s}=1.25\cdot10^1\text{ m/s} \end{gathered}[/tex]The answer is option A.