Assuming accural accounting is employed, which one of the following statements is correct?

$1.$ Depreciation expenses increase a firm's marginal tax rate.

$2.$ The addition to retained earnings is equal to net income plus dividends paid.

$3.$ The cost of aquiring a product are expensed when the produst is sold$/$

$4.$ Credit sales recorded on the income statement when the cash from the sale is collected.