My dear Sukadeva Gosvami, you (Pariksit) have already explained that Sankarsana, who belongs to the second quadruple, appeared as the son of Rohini named Balarama - SB 10.1.8

Expressions researched:
"My dear Śukadeva Gosvāmī, you have already explained that Saṅkarṣaṇa, who belongs to the second quadruple, appeared as the son of Rohiṇī named Balarāma"

Srimad-Bhagavatam

SB Canto 10.1 to 10.13

My dear Śukadeva Gosvāmī, you have already explained that Saṅkarṣaṇa, who belongs to the second quadruple, appeared as the son of Rohiṇī named Balarāma. If Balarāma was not transferred from one body to another, how is it possible that He was first in the womb of Devakī and then in the womb of Rohiṇī? Kindly explain this to me.

SB 10.1.8, Translation and Purport

My dear Śukadeva Gosvāmī, you have already explained that Saṅkarṣaṇa, who belongs to the second quadruple, appeared as the son of Rohiṇī named Balarāma. If Balarāma was not transferred from one body to another, how is it possible that He was first in the womb of Devakī and then in the womb of Rohiṇī? Kindly explain this to me.

Here is a question particularly directed at understanding Balarāma, who is Saṅkarṣaṇa Himself. Balarāma is well known as the son of Rohiṇī, yet it is also known that He was the son of Devakī. Parīkṣit Mahārāja wanted to understand the mystery of Balarāma's being the son of both Devakī and Rohiṇī.