The correct answer is: a) Depositional work of rivers.
The Punjab plains are a vast alluvial plain located in the northwestern part of the Indian subcontinent. The plain is formed by the confluence of the Indus and its tributaries, and is one of the most fertile regions in the world. The plain is also home to a number of important historical and cultural sites, including the city of Lahore.
The formation of the Punjab plains is attributed to the depositional work of rivers. The Indus River is the largest river in the Indian subcontinent, and it has been depositing sediment in the Punjab region for millions of years. This sediment has gradually built up to form the vast plain that we see today.
The other options are incorrect because they do not explain the formation of the Punjab plains. Option b) is incorrect because the uplift of tectonic plates is not a major factor in the formation of alluvial plains. Option c) is incorrect because volcanic activity is not a major factor in the formation of alluvial plains. Option d) is incorrect because erosion by glaciers is not a major factor in the formation of alluvial plains.
In conclusion, the formation of the Punjab plains is attributed to the depositional work of rivers. The Indus River has been depositing sediment in the Punjab region for millions of years, and this sediment has gradually built up to form the vast plain that we see today.