The largest contributor to the change in seasons is the tilt, or inclination, of the Earth's spin axis with respect to its orbital plane (the ecliptic).
(The largest contributor to the change in seasons; is; the tilt, or inclination, of the Earth's spin axis with respect to its orbital plane)
The largest contributor to the change in seasons
is
the tilt, or inclination, of the Earth's spin axis with respect to its orbital plane