4. which of the following would change if the earth had no tilt relative to the ecliptic?
a. each season would last longer
b. the year would be longer
c. there would be no seasons
d. there would be more days per year

Option (C)

Explanation:

The earth's axis of rotation is tilted at an angle of 23.5 degrees. This tilting has taken place due to the impact between earth and another earth-like planet. The moon resulted from this impact. This tilt plays an important role in the occurrence of seasons on earth.

If the earth was not tilted and remained the same, then it would have not experience any type of season. The conditions would have been very consistent. The equatorial region would have received maximum sunlight, as a result of which only one kind of season would be experienced throughout the year. Due to this, life would be very difficult to survive.

Thus, the tilt of the earth creates four types of seasons, such as summer, autumn, winter and spring, relative to its elliptical path where it moves around the sun.

Hence, the correct answer is option (C).