(d) K > Mg > Al> B
In a period, metallic character decreases as we move from left to right. Therefore, metallic character of I < Mg and Al decreases in the order: K > Mg > Al. However, within a group, the metallic character, increases from top to bottom. Thus, Al is more metallic than B. Therefore, the correct sequence of decreasing metallic character is K > Mg > Al > B,