Answer
Potassium and Iron are expected to be good reducing agents based on periodic trends.
Work Step by Step
Reducing agents are those substances that help other substances to be reduced in a particular reaction. So, the reducing agents have the tendencies to lose electrons and become oxidized so that the other substance can gain electrons and become reduced.
Now here Potassium (grp. 1 element in the periodic table) and Iron (grp. 8 element in the periodic table) both are metals. So, they have the tendencies to lose electron and become oxidized. So, they are good reducing agents.
