Which of the Following Is the Best Definition of flOat

Which of the following is the best definition of float?

A) The difference between book cash and bank cash, representing the net effect of cheques in the process of clearing.
B) A strategy in which an investor purchases securities to own them on the day of record and then quickly sells them; designed to attain dividends but avoid the risk of a lengthy hold.
C) Bank makes proceeds of cheques deposited available the same day before cheques clear.
D) The need to hold cash as a safety margin to act as a financial reserve.
E) Special post office boxes set up to intercept and speed up accounts receivable payments.