In which of the following options,elements are correctly arranged in the increasing order of their atomic radius?

Explain covalent radius and van der Waals radius.

If the ionic radii of $K^{+}$ and $F^{-}$ are nearly the same (i.e.,$1.34 \ \mathring{A}$),then the atomic radii of $K$ and $F$ respectively are

The atomic radii in the periodic table among elements from right to left:

Assertion $(A)$: $Mg^{2+}$ and $Al^{3+}$ are isoelectronic but the magnitude of the ionic radius of $Al^{3+}$ is less than that of $Mg^{2+}$.
Reason $(R)$: The effective nuclear charge on the outermost electrons in $Al^{3+}$ is greater than that in $Mg^{2+}$.
The correct option among the following is:

Of the following,the ion with the smallest ionic radius is