PART A
Cutting in one minute = 105 ÷ 3 = 35 cuts
Now for six machine = 35 × 6 = 210 parts.
So, the option C. 210 parts is correct answer.
PART B
As, 20 × 3 = 60 seconds
Parts can be stamped in one minute = 24 × 3 = 72
So, time required

So, the option D. 60 minutes is c correct answer