The correct option is: (A) a metal piece
Explanation:
a friend of mine → 4916 ...(i)
mine lot of metal → 3109 ...(ii)
a piece of metal → 7163 ...(iii)
From (i), (ii) and (iii), 'of is '1'.
From (ii) and (iii), 'metal' is '3'.
From (i) and (iii), 'a' is '6'.
So, from (iii), '7' is 'piece'.
So, '673' can be written as 'a metal piece'