In Wikipedia, look up "Tidal force" and answer the following question: A tidal force is a gravitational effect that stretches along the line towards the center of mass of another body due to a gradient (difference in strength) in the gravitational field across the body. Which of the following is not a consequence of tidal forces?
a. Ocean tides
b. Tidal locking
c. Breaking apart of celestial bodies and formation of ring systems
d. All the above are consequences of tidal forces