Adisadvantage of using a sentence outline instead of a topic outline is that a sentence outline is often
a. rigid.
b. time-consuming.
c. underdeveloped.
d. factually grounded.

A disadvantage of using a sentence outline instead of a topic outline is that a sentence outline is often underdeveloped, since you are trying to synthesize clumps of ideas into a short sentence. In order to avoid this, one must have wide vocabulary skills to use the exact words that fits to a sentence outline.