How to code tables with multi-line cells

Use the p column descriptor:

Change

\begin{tabular}{lll} 

to

\begin{tabular}{llp{5cm}}

To explicitly insert line-breaks:

CCCCCCCC  & DDDD & \parbox{5cm}{Betty Botter Thought: \\ If I Put This Bitter Butter in My Batter it Will Make My Batter Bitter}