Why is the time difference important even though India's east west width is less than north south length?

Correct answer: Because time is affected by longitude

The governing concept is that local time is controlled primarily by longitude, not by the total north–south length of a country. Earth rotates 15 degrees of longitude in about one hour, or approximately four minutes per degree. Thus even a comparatively smaller east–west width can create a measurable time difference between eastern and western places. India uses a single standard time to avoid the confusion that separate local times would cause in administration, transport, communication, and daily schedules. Option A is correct. Latitude does not stop time, a coastline does not fix national time, and mountains cannot remove time differences; these options confuse unrelated geographical factors with longitude.