Answer:
A. 200 s
Step-by-step explanation:
The average speed of an object in motion is defined as
![v=(d)/(t)](https://img.qammunity.org/2020/formulas/physics/high-school/jidcwnxn1c0zdocnxtzp97sqgn187ivyra.png)
where
d is the distance covered
t is the time taken
For the object in the problem, we know that
d = 100 m is the distance
v = 0.5 m/s is the average speed
Solving for t, we find the time taken to cover that distance:
![t=(d)/(v)=(100)/(0.5)=200 s](https://img.qammunity.org/2020/formulas/physics/middle-school/g5a285eoe59cvbqbfw3zvj58s4ep4zdq8g.png)