Which one of the following would have occurred if the earth had not been inclined on its own axis?

The Earth's axial tilt, currently approximately 23.4 to 23.5 degrees, is the primary cause of seasonal variations [3]. As the Earth revolves around the Sun, this tilt ensures that different hemispheres receive varying amounts of direct sunlight at different points in the orbit [t3]. If the Earth were not inclined on its axis (zero obliquity), the equator would always face the Sun directly, and every location would receive a nearly identical amount of solar energy year-round [t5]. Consequently, the distinct cycle of spring, summer, autumn, and winter would cease to exist because the angle of the Sun's rays at any given latitude would remain constant throughout the year [t7]. While day and night would still occur due to rotation, the seasonal changes in temperature and day length would disappear [c3][t5].

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 12: Earth, Moon, and the Sun > 12.2.2 Seasons on the Earth > p. 177
2. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 19: The Motions of The Earth and Their Effects > Lunar Nodal Cycle > p. 266