Answer: He was serving as a minister in France
Step-by-step explanation:
Several prominent Founders were absent from the Constitutional Convention. Thomas Jefferson was in Paris, serving as the minister to France, from where he deemed the delegates as “an assembly of demigods”.
John Adams didn´t participate either, also because he was abroad, serving as minister to Great Britain.
Samuel Adams and John Hancock did not participate either, and Patrick Henry turned down the invitation claiming that he “smelt a rat in Philadelphia, tending toward the monarchy