Ais a list of duties and capabilities required for a particular job.

Option (a) is correct.

Explanation:

Manufacturing cost:

= Direct materials + Direct labor + Variable overhead + Fixed overhead

= $80,000 + $100,000 + $30,000 + $60,000

= $270,000

Purchase from outside:

= Fixed overhead + Purchase price

= $60,000 + (50,000 × $10)

= $60,000 + $500,000

= $560,000

Effect on income = Purchase from outside - Manufacturing cost

                            = $560,000 - $270,000

                            = $290,000

Therefore, the above calculations shows that income will decrease by $290,000.