The correct option is B unconditional order to pay
According to section 5 of the Negotiable Instruments Act, 1881, a bill of exchange is defined as an instrument in writing containing an unconditional order, signed by the maker, directing a certain person to pay a certain sum of money only to, or to the order of a certain person or to the bearer of the instrument. A bill of exchange is generally drawn by the creditor upon his debtor. It has to be accepted by the drawee (debtor) or someone on his behalf. It is just a draft till its acceptance is made.