The nearest star is so far away from the earth that the directions to it from two diametrically opposite points on the earth differs less than A. 0.01 second B. 0.001 second C. 0.0001 second D. None of these

The correct answer is: C. 0.0001 second

The nearest star to Earth is Proxima Centauri, which is about 4.2 light-years away. This means that it takes light 4.2 years to travel from Proxima Centauri to Earth. The Earth’s diameter is about 12,742 kilometers. If we were to stand on opposite sides of the Earth and look at Proxima Centauri, the difference in the direction to the star would be about 0.0001 second of arc. This is equivalent to the width of a human hair at a distance of 10 kilometers.

Option A is incorrect because 0.01 second of arc is about the width of a dime at a distance of 10 kilometers. This is much larger than the difference in the direction to Proxima Centauri from opposite sides of the Earth.

Option B is incorrect because 0.001 second of arc is about the width of a human hair at a distance of 1 kilometer. This is still larger than the difference in the direction to Proxima Centauri from opposite sides of the Earth.

Option D is incorrect because it is not a valid option.