OPTION A IS CORRECT
5 part -→ 20
so, 1 part -→ 4
so number of skilled worker 32 (8*4)
unskilled worker 20 (given)
clerks 4 (4*1 )
lets say wage of one person in skilled category is 5y
for unskilled 2y , clerk 3y
so 5y * 32 + 2y * 20 + 3y * 4 = 318
y= 1.5
by this we can find wags of ALL category