Which of the following conditions, if present on an otherwise negotiable instrument, would affect the instrument's negotiability?
A. The instrument is payable six months after the death of the maker.
B. The instrument is payable at a definite time subject to an accelerated clause in the event of a default.
C. The instrument is postdated.
D. The instrument contains a promise to provide additional collateral if there is a decrease in value of the existing collateral.