Which historical process is best reflected by the evolution of temple architecture in India?

Correct — B. NCERT's An Introduction to Indian Art (Class 11) traces the temple from modest Gupta-period shrines at Sanchi and Udaigiri to the Chandela temples of Khajuraho, built in the tenth century.
It also describes two broad regional orders: Nagara in the north and Dravida in the south.

That is gradual change shaped by religion and region together, which is option (b).

Why the others are wrong

• (a)
  Decline of indigenous art — Temple building grew grander, not weaker. NCERT calls the Kailashnath temple at Ellora the culmination of at least a millennium-long tradition in rock-cut architecture.
• (c)
  Sudden cultural change — The change was gradual, not sudden. NCERT says temples grew more complex by adding projecting walls and niches without breaking away from the fundamental plan of the shrine.
• (d)
  Foreign architectural dominance — Outside influence was absorbed, not dominant. NCERT says Kashmir took a strong Gandhara influence by the fifth century CE, which then mixed with Gupta and post-Gupta traditions brought from Sarnath, Mathura and elsewhere.

The Hindu temple kept one core plan: a garbhagriha housing the main icon, a mandapa for worshippers, and a spire over the sanctum.

On that plan, regional orders grew: the curving shikhara of the Nagara north, the pyramidal vimana of the Dravida south, and in the Deccan a hybrid that some ancient texts call vesara.

Local traditions kept adding layers. In Assam, a style brought by Tai migrants mixed with the Pala style of Bengal to form the Ahom style.

Key facts

• NCERT names two broad orders of temples: Nagara in the north and Dravida in the south.
• Some scholars treat Vesara as a separate style made by selectively mixing the Nagara and Dravida orders.
• The Lakshmana temple at Khajuraho was built in 954 by the Chandela king Dhanga.
• Early temples at Deogarh, Eran, Nachna-Kuthara and Udaygiri were simple structures of a veranda, a hall and a shrine at the rear.

Common traps

• Choosing 'foreign architectural dominance' because some regions, such as Kashmir, show Gandhara influence.
• Calling the rise of new regional styles a sudden change, when NCERT traces it across centuries.

No directly related past PYQ was found.