1I am writing on behalf of the Seasoning Department (SD) concerning the recent addition of cinnamon in the pancake mixture. 2As the SD leader, I want to commend your willingness to try new things. 3I would also, however, like to inform you that there have been several complaints regarding the new addition of cinnamon. Sentence 3 in the paragraph above is NOT a thesis because .

it makes no claims or assertions
it does not introduce a topic or present a stance
it is too short
both a and c
Sentence 3 is a thesis statement.