Could anyone explain this question in detail?

Answer:
h and k are simply variables that stand in for the x and y of a point. Math books could have easily have used x1, x2 y1 y2, etc, but h and k is the convention.
anyway, this is a guess n check question. Substitute the x value of the point for h, and y value for k, and whichever one gives you a true equation is the right one.
Answer:
Step-by-step explanation:
y = a(x-h)²+k is the “vertex-form equation” for a vertical parabola with vertex (h,k).
Since a>0, the parabola opens upwards. (If a<0, it opens downwards. If a=0, it is not a parabola at all.)
The parabola y = a(x-h)²+2k is the same shape as the first equation, but it is shifted vertically by k units.
Since (2,4) is a point on the first parabola, (2,4+k) is a point on the second parabola.