Option 1 states that the middle stage of the Damuda series, called Barren Rocks, consists of coal and not iron. This option is incorrect because the middle stage is actually called Barren Rocks because it consists of iron and not coal. The term "barren" in this context refers to the absence of coal in this particular stage.

Option 2 states that the middle stage of the Damuda series consists of iron and not coal. This is the correct answer because the middle stage is known as Barren Rocks precisely because it lacks coal but contains iron deposits. This stage is characterized by sedimentary layers rich in iron minerals.

Option 3 states that the middle stage consists of neither coal nor iron. This option is incorrect as it contradicts the actual characteristics of the Barren Rocks stage.

Option 4 states that the middle stage is a sedimentary layer consisting of shale and clay. While it is true that sedimentary layers are present in the Damuda series, this option does not explain why the middle stage is called Barren Rocks because it does not mention the absence of coal or presence of iron.

In summary, the correct answer is option 2 because the middle stage of the Damuda series is called Barren Rocks due to its iron deposits and lack of coal