With reference to International Date Line, consider the following statements:
(a) A person crossing it from east to west gains a day.
(b) It is an imaginary straight line drawn at 180° meridian.
Choose the correct answer:

Question

Accepted Answer

Here's a detailed explanation justifying why Option 1 is the correct answer and why the other options are incorrect, focusing solely on supporting Option 1:

**Why Option 1 (Only (a)) is Correct:**

Statement (a), "A person crossing it from east to west gains a day," is correct. The International Date Line (IDL) is designed to compensate for the time difference accumulated as one travels around the world. When you travel eastward, you are effectively moving *towards* the rising sun, experiencing sunrises earlier and earlier. Conversely, traveling westward means you are moving *away* from the rising sun, experiencing sunrises later and later.

To maintain calendar consistency, the IDL acts as a boundary where the date changes. Crossing the IDL from east to west means you are essentially "catching up" with the sun, and to account for this, you gain a day. For example, if you cross the IDL westward on a Tuesday, it becomes Wednesday. This prevents you from losing a day as you circumnavigate the globe westward.

**Why the Other Options are Incorrect:**

*   **Option 2 (Only (b)):** Statement (b), "It is an imaginary straight line drawn at 180° meridian," is incorrect. While the IDL roughly follows the 180° meridian, it is *not* a straight line. It deviates in several places to avoid cutting through landmasses and island groups. This deviation is crucial to prevent situations where a single country or island group would have two different dates. The IDL's zig-zag pattern is a deliberate design to maintain social and economic cohesion within these regions.

*   **Option 3 (Both (a) & (b)):** This option is incorrect because, as explained above, statement (b) is false. The IDL is not a straight line. Since one part of this option is incorrect, the entire option is incorrect.

*   **Option 4 (Neither (a) nor (b)):** This option is incorrect because statement (a) is true. Crossing the IDL from east to west *does* result in gaining a day. Since one part of this option is incorrect, the entire option is incorrect.

In conclusion, only statement (a) is correct, making Option 1 the only valid answer. The IDL's function of adding a day when crossing from east to west is a fundamental aspect of its purpose in maintaining global calendar consistency.