The correct option is 2 only
Explanation
Indo-Islamic architecture introduced new construction techniques and materials to the Indian subcontinent, most notably the use of cementing material in the form of lime mortar. This allowed for the construction of true arches and domes. The choice of building material-stone, rubble, or brick-often depended on regional availability and the economic conditions of the specific dynasty.
Statement 1 is Incorrect:
In many Indo-Islamic structures, particularly during the Delhi Sultanate (e.g., the Tughlaq dynasty), walls were constructed using rubble masonry. Since rubble creates a rough surface, these walls were typically cased over with dressed stone or finished with a thick layer of chunam (lime plaster) to ensure a smooth and aesthetic appearance.
Statement 2 is Correct:
The use of bricks in construction did not begin in the 17th century; it has existed in India since the Indus Valley Civilization. In the context of Indo-Islamic architecture, bricks were used extensively well before the 17th century, particularly in regions where stone was scarce, such as Bengal (Provincial Style), and in the structures of the Lodi dynasty.
Statement 3 is Incorrect:
Polychrome (multi-colored) glazed tiles were not avoided; on the contrary, they were a distinct decorative feature introduced due to Persian influence. They were used to embellish walls and domes during the Sultanate period (e.g., Lodi tombs) and became a prominent feature in Mughal architecture (e.g., the tiled walls of the Lahore Fort or Chini-ka-Rauza).
Key Takeaway:
Indo-Islamic architecture is characterized by the use of lime mortar, rubble masonry faced with stone or plaster, and the decorative application of polychrome glazed tiles, with brick usage prevalent in specific regions long before the Mughal zenith.