Definitions of secret on the Web:

* not open or public; kept private or not revealed; “a secret formula”; “secret ingredients”; “secret talks”
* clandestine: conducted with or marked by hidden aims or methods; “clandestine intelligence operations”; “cloak-and-dagger activities behind enemy lines”; “hole-and-corner intrigue”; “secret missions”; “a secret agent”; “secret sales of arms”; “surreptitious mobilization of troops”; “an undercover investigation”; “underground resistance”
* unavowed: not openly made known; “a secret marriage”; “a secret bride”
* communicated covertly; “their secret signal was a wink”; “secret messages”
* not expressed; “secret (or private) thoughts”

b) I agree.