Over an interval of 6 months, the tilt of the Earth’s spin axis with respect to the surrounding star fields changes by

0°

Explanation:

Every 41,000 years, the axial tilt of the Earth varies by oscillating between 22.1  degrees and 24.5 degrees such that the Earth axis orientation with respect to background stars is relatively constant (change is 0) while rotating over one orbital period which is a duration of 12 months. The effect is that the direction of the North or South pole towards the Sun is dependent on the side of the Earth orbit the Earth is located bringing about seasonal variation.

the entire statement is true and correct.  

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