AWS Key Management Service uses the Advanced Encryption Standard $($AES$)$ algorithm for Server$-$Side Encryption. Which of the following statements about AES are not true?

$1.$AES decryption algorithm is different from AES encryption algorithm.

$2.$AES has two options for key size.

$3.$AES MixColumn transformation uses an inversible constant matrix.

$4.$AES MixColumn transformation is built on GF$(2^4).$

$5.$AES Substitution transformation substitutes $8$ bits of a matrix with $8$ bits.

$6.$AES encrypts $256-$bit plaintext to produce $256-$bit ciphertext.