Why is studying India's longitudinal extent necessary to understand the relation between local time and standard time?

Correct answer: Because local time changes with longitude

Option A is correct because local time is determined by the Earth’s rotation and a place’s longitude. Earth rotates 360 degrees in about 24 hours, so 15 degrees of longitude corresponds to roughly one hour, or about four minutes per degree. Consequently, places farther east experience local noon earlier than places farther west. India has a considerable east–west longitudinal span, creating a noticeable difference between local times at its eastern and western ends. To avoid confusion in administration, transport, communication, and daily scheduling, the country follows one standard time based on the Standard Meridian at 82°30′E. Latitude, area, and land boundaries do not directly establish this time relationship.