which message filter to drop all executable attachments entering and leaving the Cisco Email Security Appliance?

A Cisco Email Security Appliance uses which message filter to drop all executable attachments
entering and leaving the Cisco Email Security Appliance?

A.
drop-exe: if (attachment-filename == “\\.exe$”) OR (attachment-filetype == “exe”) { drop(); }

B.
drop-exe: if (recv-listener == “InboundMail” ) AND ( (attachment-filename == “\\.exe$”) OR
(attachment-filetype == “exe”)) { drop(); }

C.
drop-exe! if (attachment-filename == “\\.exe$”) OR (attachment-filetype == “exe”) { drop(); }

D.
drop-exe! if (recv-listener == “InboundMail” ) AND ( (attachment-filename == “\\.exe$”) OR
(attachment-filetype == “exe”)) { drop(); }

Explanation: