______ by many well-known experts and film stars, the product was very popular at one time.

1. A.
   To advocate
2. B.
   Having advocated
3. C.
   Advocating
4. D.
   Advocated

 ______ by many well-known experts and film stars, the product was very popular at one time.

     A. To advocate          B. Having advocated      C. Advocating               D. Advocated