The correct answer is (a) August 1992.
The Malpa landslide was a major landslide that occurred on August 1, 1992, in the Malpa village of Pithoragarh district in the Indian state of Uttarakhand. The landslide was caused by heavy rains and destroyed a railway track and a road, killing at least 100 people.
The landslide occurred at around 11:30 pm on August 1, 1992. A large mass of rock and earth broke away from the mountainside and crashed down onto the railway track and the road below. The landslide completely destroyed the railway track and blocked the road for several days.
The landslide killed at least 100 people, including many railway workers and passengers. Many more people were injured. The landslide also caused extensive damage to property and infrastructure.
The Malpa landslide was one of the deadliest landslides in Indian history. It was a major disaster that had a devastating impact on the lives of many people.
The other options are incorrect because they are not the dates on which the Malpa landslide occurred.