The correct option is A True
Valency of iron can either be 2 or 3. Depending upon the conditions , iron atoms that participate in the chemical reaction will either be 2 or 3. Hence iron exbits variable valency.
For example,
(a) During the formation of ferrous oxide (FeO), the valency of iron is 2.
(b) During the formation of ferric oxide (Fe2O3), the valency of iron is 3.