What describes how CTR mode encryption functions?

a. Uses a self-synchronizing stream cipher where the initialization vector (IV) is encrypted and XORed with the data stream one bit at a time
b. Encrypts each block with the same key, where each block is independent of the others
c. Converts the block cipher into a stream cipher, then uses another value and a nonce to encrypt the data
d. Uses an initialization vector (IV) to encrypt the first block, then uses the result of the encryption to encrypt the next block