Moule’s review served as a welcome encouragement

Moule’s review served as a welcome encouragement to the author: Hardy set to work with renewed vigor and finished the serial ahead of time.

A. served as a welcome encouragement to the author: Hardy
B. served a welcome encouragement to Hardy, and the author
C. was welcome as an encouragement to Hardy, the author
D. was a welcome encouragement to the author, Hardy
E. served as a welcome encouragement to the author, Hardy