How....to....solve....this.... problem..... I.... am.... not....able....to...get...my. ...head....around ....this ...

In this question we need to only apply mathematical approach .We can simply make a square joining the center's of anoins(bigger circles here).then we can find the length of diagonal of square of MT structure given here  that is 2.40√2 .Then we will find the half of this distance because the cation anion distance given here we can compare with it .So it comes 1.69 Å approx .So it let to understand us the distance available in void is sufficient to fit for cation .Since for MT type it is 1.70Å given .So I think the structure in cation fits in void is perfect for representation of this Salt type .Hence option (A) should be true .

Thanks...