What is the function of the smart caching setting within a Web caching policy?

A.
to send the cache control compress header to the client

B.
to remove the cache control headers from the origin server

C.
to not modify the cache control header from the origin server

D.
to send the appropriate cache control header based on Web content.

Explanation:
http://www.juniper.net/techpubs/software/ive/admin/j-sa-sslvpn-7.2-adminguide.pdf
(page 513, see smart caching)