In which of the following forms is iron absorbed by plants?

Iron is the most abundant mineral ion required by the plant. It is absorbed in ferrous and ferric form from the rhizosphere of the plant. Fe2+(ferrous) form is relatively soluble but is readily oxidized to Fe3+(ferric) at the junction of the protoxylem and the metaxylem, chelated by citrate, and then transported in the metaxylem to the other parts of the plant. So, the correct answer is 'Ferric'.