Consider the following symmetric encryption scheme (KG,E,D), which uses a pseudo-random permutation P, and a message authentication scheme (Gen, Tg,Vrfy) with unique tags. The key generation algorithm KG returns randomly chosen keys k1, k2. On input keys k1,k2 (returned by KG) and message m, the encryption algorithm E randomly chooses r, computes x=(r, m xor P(k1;r)) and returns ciphertext c=(x,Tg(k2;x)). On input keys k1,k2 (returned by KG) and ciphertext c, the decryption algorithm D writes c as (c1,c2), verifies whether Vrf(k2;(c1,c2))=1; if yes, it writes x as (x1,x2) and returns message m'=P(k1;x1) xor x2, otherwise it returns an error message. Which is the strongest security notion satisfied by the scheme (KG,E,D)?
A. Security in the sense of indistinguishability
B. Security in the sense of indistinguishability with chosen message attack
C. Security in the sense of indistinguishability with adaptive chosen message attack
D. Security in the sense of indistinguishability with chosen ciphertext attack
Please explain your reasoning.