Electric Fields Question

Although kinetic energy converts to electric potential energy, why would the speed at point O become 0?

The question asks what is the *minimum* KE the +q charge needs to have to just reach O. If it starts off with just the minimum KE then when it reaches O, all that energy would have been converted to PE and it would have 0 KE. So it would stop at O. Minimum KE need to reach O is equal to PE at O.

If it had more energy at the start than the minimum, then at O it would have the same amount PE as before but in addition there would also be some KE, so its velocity would not be 0 at O.