The correct option is 1 and 3 only.
Explanation
The Gupta period (4th-6th century CE) is considered the "Golden Age" of Indian art. During this time, the Mathura and Sarnath schools of art emerged as the two pre-eminent centers for sculpture. A defining feature of Gupta art, distinguishing it from the earlier Kushana period, is the evolution of the halo (Prabhamandala) and the treatment of drapery.
Statement 1 is Correct: The Mathura Buddha images from the Gupta period are characterized by a profusely decorated halo. Unlike the plain or scalloped halos of the earlier Kushana period, the Gupta-Mathura halos feature concentric bands of elaborate floral and geometric ornamentation.
Statement 2 is Incorrect: The Sarnath Buddha images are also known for their elaborately decorated halos, often featuring floral scrolls and lotus motifs. The statement claiming "very little ornamentation" is factually incorrect regarding the halo. The distinct feature of the Sarnath school that is "plain" or "transparent" is the drapery (robes), which lacks the schematic folds seen in the Mathura style. The plain halo is a characteristic of the earlier Kushana period, not the Gupta-Sarnath style.
Statement 3 is Correct: Both the Mathura and Sarnath schools flourished under the patronage of the Gupta rulers. While Mathura was an older center that continued to evolve, Sarnath developed a distinct idiom during the Gupta era, eventually influencing art across India and Southeast Asia.
Key Takeaway: Gupta Art is characterized by decorated halos (both in Mathura and Sarnath). The key difference lies in the drapery: Mathura has schematic folds, while Sarnath has plain/transparent drapery.