The correct answer is (a). The Earth’s axis of rotation is always inclined at an angle of 23.5 degrees from the plane of its orbit around the Sun. This tilt is what causes the seasons.
The Earth’s axis is tilted because of the way it formed. When the Earth was first forming, it was a hot, spinning ball of gas and dust. As it spun, it flattened out into a disk. The Earth’s axis of rotation is the line that goes through the North and South Poles. It is tilted at an angle of 23.5 degrees from the plane of the Earth’s orbit around the Sun.
This tilt is what causes the seasons. In the Northern Hemisphere, summer occurs when the Northern Hemisphere is tilted towards the Sun. In the winter, the Northern Hemisphere is tilted away from the Sun. The opposite is true for the Southern Hemisphere.
The tilt of the Earth’s axis also causes the Sun to appear to move across the sky in a different way throughout the year. In the summer, the Sun appears higher in the sky and the days are longer. In the winter, the Sun appears lower in the sky and the days are shorter.
The tilt of the Earth’s axis is a very important factor in the Earth’s climate. It is what causes the seasons and the different amounts of sunlight that different parts of the Earth receive.