Answer:
Theory
Step-by-step explanation:
We are given the statement;
"A helium filled balloon floats."
Now, this statement is an attempt to explain to us why balloons float. And the reason is because they are filled with helium. This is no prediction or law or observation because to find out if the balloons contain helium, there must have been experiments to confirm that.
Thus, the statement in the question is a theory.