Hotel clock

Test and analysis: four clocks at different times in this question illustrate the existence of time difference. This phenomenon is caused by the constant rotation of the earth. Different parts of the earth's surface are illuminated by the sun at different times, so there will be four clocks with different times. So a is the right option.

Comments: The four clocks at different times in this question reflect the time difference and instant difference in different parts of the earth's surface. The earth is constantly moving around its axis from west to east. Because the earth is an opaque sphere, the sun can only illuminate half of the earth at any time, the illuminated hemisphere is daytime, and the unlighted hemisphere is night. Because the earth is constantly moving from west to east, there is a phenomenon of alternating day and night. Different areas are exposed to the sun at different times, so there is a time difference.