According to Time-theory - the 'Sandhi-Prakash' category is:

Question

Accepted Answer

The correct option is 1:
The correct option is 1: The Raga-Time Theory, or *Samay Siddhant*, is a cornerstone of Hindustani Classical Music, proposing that a Raga's emotional effect is maximized when performed at a specific time of day. The 'Sandhi-Prakash' Ragas (literally 'Twilight-Illuminating' Ragas) are the unique group sung at the *sandhi* (junction or twilight period) of day and night—specifically, from 4:00 AM to 7:00 AM (early dawn) and from 4:00 PM to 7:00 PM (early dusk). The defining tonal characteristic of this entire category, encompassing both morning and evening twilight Ragas, is the mandatory use of *Komal Rishabh* ($\flat$Re) and *Komal Dhaivat* ($\flat$Dha). These two flattened notes are the sonic signature of the transitional phase of the day. Examples like Raga Bhairav (morning) and Raga Purvi (evening) both employ this specific $\flat$Re-$\flat$Dha pair, which serves as the fundamental technical basis for their classification in this category.

The incorrect option is 2:
The option 'Re-Dha Shuddh' is incorrect because Ragas that exclusively use *Shuddh* (Natural) Re and Dha are not Sandhi-Prakash Ragas. This combination of pure notes is the basis for the Bilawal and Kalyan *Thaats*. These Ragas are typically associated with the middle parts of the day (10 AM to 4 PM and 7 PM to 10 PM), which are past the actual twilight or junction period. The absence of the flattened second and sixth notes signifies a bright, stable mood, contrasting sharply with the reflective mood of the twilight Ragas.

The incorrect option is 3:
The option 'Ga-Ni Flat' is incorrect. The combination of *Komal Gandhar* ($\flat$Ga) and *Komal Nishad* ($\flat$Ni) is the primary characteristic of Ragas belonging to the Kafi *Thaat* family. These Ragas are performed in the second quarter of the day and night. Their time window is typically from 9 AM to 12 PM and 9 PM to 12 AM, respectively. This timing is distinctly separate from the twilight *sandhi* hours that define the Sandhi-Prakash category.

The incorrect option is 4:
The option 'Ga-Dha Flat' is incorrect as the single defining feature of the entire Sandhi-Prakash category. The pairing of *Komal Gandhar* ($\flat$Ga) and *Komal Dhaivat* ($\flat$Dha) is the characteristic feature of the Asavari *Thaat*. Ragas from this *Thaat* are traditionally sung in the third quarter of the day (12 PM to 3 PM), which is the afternoon. Although $\flat$Dha is present, the presence of $\flat$Ga and the exclusion of $\flat$Re places them in the afternoon, thereby disqualifying them from the twilight Sandhi-Prakash category.