Step 1: Understanding the Concept:
The question asks which form of art reached its peak or highest point of development during the reign of the Mughal Emperor Shah Jahan.
Step 2: Detailed Explanation:
The reign of Shah Jahan (1628-1658) is widely considered the "Golden Age of Mughal Architecture". He was a prolific builder with a keen aesthetic sense. His architectural marvels are characterized by elegance, symmetry, and the extensive use of white marble and pietra dura (inlay work).
The most famous example is the Taj Mahal in Agra. Other major constructions include the Red Fort (Lal Qila) and the Jama Masjid in Delhi, and the Shalimar Gardens in Lahore.
While other arts also flourished:
Painting: Mughal painting reached its zenith under Shah Jahan's father, Jahangir. Under Shah Jahan, painting became more formal and rigid, though still of high quality.
Sculpture: Monumental sculpture was not a major feature of Mughal art.
Calligraphy: This was an important art form, but architecture was the defining achievement of his reign.
Step 3: Final Answer:
Architecture undoubtedly reached its zenith during Shah Jahan's reign. Therefore, option (B) is correct.