Option 1: "1 only" is correct. This refers to the first statement "Carbon fibres are used in the manufacture of components used in automobiles and aircrafts." This is true as carbon fibres are a lightweight, strong and durable material that is used in the manufacturing of various components for automobiles and aircrafts due to their high stress tolerance and low weight.

Option 2: "2 only" This suggests that only the second statement "Carbon fibres once used cannot be recycled" is true. But, it`s incorrect as carbon fibres can be recycled, even though the process is complex and expensive.

Option 3: "Both 1 and 2" This implies that both the statements are correct. But because Statement 2 is incorrect, this option isn`t valid.

Option 4: "Neither 1 nor 2" This option suggests that both statements are incorrect. But since Statement 1 is correct, this option isn`t accurate.

Therefore, the correct answer is Option 1 - Statement 1 is correct and Statement 2 is incorrect.