Which of the following encryption algorithms are based on block ciphers?

Which
of the following encryption algorithms are based on block ciphers?

A.
RC4

B.
Twofish

C.
Rijndael

D.
RC5

Explanation:
The following encryption algorithms are based on block ciphers:
RC5
Rijndael
Twofish
In cryptography, a block cipher is a symmetric key cipher which operates on fixed-length groups of
bits, termed as ‘blocks’, with an unvarying

transformation. When encrypting, a block cipher might take (for example) a 128-bit block of plain
text as input, and output a corresponding
128-bit block of cipher text.