A. Thousands of years ago people could tell the time ...

• 1) only when they could see the sun in the sky.
• 2) only when there were no clouds in the sky.
• 3) any time of the day in any kind of weather.

Люди могли определять время, только когда видели солнце на небе, то есть когда не было облаков.

Ответ: 2) only when there were no clouds in the sky.