Why can the same moment show up as different local times in different places?

Answer: Because each region applies its own timezone offset and daylight-saving rules

Because computers cannot agree on what counts as a full day — Wrong. The problem is not that computers disagree about days, but that local civil time depends on location-specific rules.

Because each region applies its own timezone offset and daylight-saving rules ✓ — Correct! The same instant can appear differently because each region applies its own timezone offset and daylight-saving rules.

Because internet clocks pick a random time each time they sync — Wrong. Internet-connected clocks are not random; they are representing the same underlying moment differently.