'none' - Use this with clients that don't have a client secret:

‘none’ – Use this with clients that don’t have a client secret:

‘none’ – Use this with clients that don’t have a client secret:
A . Such as applications that use the authorization code flow with PKCE
B. Not with applications that use the authorization code flow with PKCE
C. Such as applications that use the implicit flow
D. Not with applications that use the implicit flow

Answer: A,C