I don’t know what book you’re talking about so I can’t help but have a look online, you may be able to find it if you search up the book name and look around a few websites
A because of the resistors are four in this options first option is multiplied by 4
Answer:
a) 0.25m
b) 5 m/s
Explanation:
When the spring is compressed both boxes are moving with the same velocity, so applying the principle of linear momentum conservation:

Now applying the principle of energy conservation:

We got that the maximum compression is 0.25m.
The answer is either c or d but c is the best answer