A two hinged parabolic arch of span l and rise h carries a load varying from zero at the left end to per unit run at the right end. The horizontal thrust is

• A. <img src="/_files/images/civil-engineering/theory-of-structures/97-21-179-1.png">
• B. <img src="/_files/images/civil-engineering/theory-of-structures/97-21-179-2.png">
• C. <img src="/_files/images/civil-engineering/theory-of-structures/97-21-179-3.png">
• D. <img src="/_files/images/civil-engineering/theory-of-structures/97-21-179-4.png">