Which description is true about ECB mode?

Which description is true about ECB mode?

A.
ECB mode uses the same 64-bit key to serially encrypt each 56-bit plain-text block.

B.
In ECB mode, each 56-bit plain-text block is exclusive ORed (XORed) bitwise with the previous ciphertext block.

C.
ECB mode uses the same 56-bit key to serially encrypt each 64-bit plain-text block.

D.
In ECB mode, each 64-bit plain-text block is exclusive ORed (XORed) bitwise with the previous ciphertext block.