Answer: All three can be true.
Step-by-step explanation:
Realism is an attempt to represent things as they are without embellishment. So, this is true.
A tenement is not necessarily a multi-story building but it does usually mean that when discussed and it is a group of areas originally designed to house immigrants. While most commonly called apartments, but they can be a collection of rooms divided up to house people. This answer depends on what the teacher is willing to accept. I would go with true.
A union is when a group of workers gets together to protest poor working conditions and they collectively demand reforms and better wages. So this is true.