The correct option is (a).
Explanation
The Earth's grid system consists of latitudes (parallels) and longitudes (meridians). The Prime Meridian (0°) and the 180° Meridian are specific lines of longitude used to define time zones, the International Date Line, and the division of the Earth into hemispheres.
Statement-wise Analysis:
- Statement 1 is Correct: The Prime Meridian (0°) and the 180° Meridian are directly opposite each other. Together, they form a complete Great Circle that divides the Earth vertically into two equal halves: the Eastern Hemisphere and the Western Hemisphere.
- Statement 2 is Incorrect: Unlike latitudes, which are parallel circles that never meet, meridians of longitude are semi-circles. They are widest apart at the Equator and converge to meet at a single point at both the North Pole and the South Pole. Therefore, they are not parallel lines.
- Statement 3 is Incorrect: The 180° Meridian is a unique line where the count of longitude from the East (0° to 180° E) and the West (0° to 180° W) concludes. 180° East and 180° West are the exact same line, not two distinct lines separated by distance.
Key Takeaway:
Meridians of longitude converge at the poles and are not parallel. The Prime Meridian and the 180° Meridian together form a Great Circle that separates the Eastern and Western Hemispheres.