Answer:
C. This piece of furniture is a chair. This chair is soft; all chairs are soft.
Step-by-step explanation:
In a fallacy of logos, you will encounter something invalid, insufficient or disconnected between the arguments given to arrive at a conclusion. In this case, there is a disconnection between the outcome "all chairs are soft" and the argument "this piece of furniture is a chair".
The conclusion doesn´t follow logically what is preceded by the arguments.
I hope this answer helps you.