Atomic radius question!!! HELP ME

HELP, This was a question from the DAT Destroyer Gen. Chem. pg.115

Question: Rank by size :
Al, K, Br, I

Answer: K > Al > I > Br

I thought the more electrons it has, the bigger the atom
Al = 13e
K = 19e
Br = 35 e
I = 53e

So according to my logic, shouldn't the answer be I > Br > K > Al

Source: Student Doctor Network - January 4, 2018 Category: Universities & Medical Training Authors: Banana_nut95 Source Type: forums