Standing in a open ground on a cloudless day ,at what time your shadow be the shortest ?

12:00

The correct answer is option 4. 12:00

Assuming you are in the northern hemisphere, on a cloudless day, your shadow would be the shortest at  12:00 (noon).

At noon (12:00), the Sun is typically at its highest point in the sky, directly overhead. Therefore, your shadow would be the shortest at this time because the Sun is directly above you, casting your shadow directly below you. As the Sun moves lower in the sky during the morning and afternoon, your shadow would lengthen.