Option 1 states that both statements are individually true and that Statement II is the correct explanation of Statement I. Statement I states that the cities of the second urbanization in Indian history are mainly located in the Ganga valley. Statement II states that advanced iron technology, ensuring an agrarian surplus, is instrumental to this process of urbanization. While both statements may be individually true, Statement II is not a correct explanation of Statement I. The location of the cities in the Ganga valley does not necessarily have a direct connection to advanced iron technology and an agrarian surplus. Therefore, Option 1 is incorrect.

Option 2 states that both statements are individually true but Statement II is not the correct explanation of Statement I. This aligns with the correct answer because although both statements are true, Statement II does not provide a direct explanation for Statement I.

Option 3, which is the correct answer, states that Statement I is true but Statement II is false. This is accurate because the statement that the cities of the second urbanization in Indian history are mainly located in the Ganga valley is true, while the explanation that advanced iron technology and an agrarian surplus are instrumental is false.

Option 4 states that Statement I is false but Statement II is true. This is not the