Doubt from ionic equilibrium

1573020859601176647009758693674 please explain question 10

Isn't it B?

No it isn't

I think it should be option A
Because according to oswald dilution law alpha(dissociation const ) = root (Ka/C) for weak acid and hence we can see that on dilution alpha increase
H+ concentration is C alpha and hence concentration is directly proportional to Root (C) and hence with dilution H+ concentration decrease

Hence option A must be correct