Q20

Three identical atomic clocks are made so that they tick at precisely the same rate. One is kept in a laboratory, $X$, on Earth’s equator. Another is placed on board a satellite, $Y$, in a circular orbit with a period of 12 hours. A third is placed in a satellite, $Z$, that is in a geostationary orbit. The satellites orbit Earth in the equatorial plane.

Assume that the satellites are inertial frames of reference and the clocks are affected ONLY by the predictions of special relativity.

Which statement correctly compares the rates at which the clocks tick, as determined by an observer at $X$, when the satellites are in the positions shown in the diagram?
A. The clock at $Y$ ticks faster than either the clock at $X$ or the clock at $Z$.
B. The clock at $Y$ ticks slower than either the clock at $X$ or the clock at $Z$.
C. The clocks tick at different rates, with $X$ being the fastest and $Y$ being the slowest.
D. The clocks tick at different rates, with $Z$ being the slowest and $X$ being the fastest.