An extension of credit commonly includes any form of an advance, loan, or credit line. Option A involves an overdraft or cash item and is considered an extension of credit. Option B covers loans or lines of credit, both of which are extensions of credit. Option D involves the acquisition of a note linked to an insider, which also qualifies as an extension of credit. Option C, involving an advance against accrued salary, is not typically considered an extension of credit as it is essentially a prepayment of earned wages.