Correct answer: A. 326 BCE
Explanation: The direct answer is option A: 326 BCE. Alexander of Macedon came to north-western India during his eastern campaign in 326 BCE. To understand the date, remember the sequence: Alexander crossed into the Indian subcontinent, met King Porus, and fought the Battle of the Hydaspes, which is generally identified with the Jhelum River. BCE means Before Common Era, so this event occurred before year 1 CE. Option A is correct because it gives the accepted year of Alexander’s Indian invasion. Option B, 261 BCE, is mainly associated with the Kalinga War of Ashoka, not Alexander. Option C, 78 CE, is a much later date linked with the Shaka era. Option D, 320 CE, belongs to the beginning of the Gupta Era, several centuries later. Therefore, A is the only suitable choice. Memory cue: connect 326 BCE with “Alexander, Porus and Jhelum.”