Which of the statements below is correct? September October Sales in units 21,000 15,000 Operating Expenses: Expense $19,750 $19,750 Expense 2 $80,250 $57,750 Expense 3 $28,350 $20,250 Expense 4 $15,500 $12,500 Expense 5 $52,500 $37,500 Total Operating Expenses $196,350 $147,750 Expenses 4 & 5 are variable costs. O Expenses 2 & 3 are variable costs. O Expenses 2 & 4 are variable costs. O Expenses 3 & 5 are variable costs