The difference in the lengths of two diagonals of a rail diamond is

• A. <img src="/_files/images/civil-engineering/railways/61-17-173-1.png">
• B. <img src="/_files/images/civil-engineering/railways/61-17-173-2.png">
• C. <img src="/_files/images/civil-engineering/railways/61-17-173-3.png">
• D. <img src="/_files/images/civil-engineering/railways/61-17-173-4.png">