$13.$ Starbucks has negative shareholder equity

$($a$)$ And a unique business model, but they aren$$t particularly profitable

$($b$)$ They have chosen almost exclusively a debt financing approach to their growth

$($c$)$ They have significant treasury stock, resulting from share buybacks, a negative offset to the equity account

$($d$)$ All of these

$14.$ The business model of an airline

$($a$)$ Requires significant investment in fixed assets

$($b$)$ Is dependent on a revenue stream that can be very variable

$($c$)$ Tends to collect its revenue quite quickly, receivable collection periods are low

$($d$)$ All of these