B.G 4.04
अर्जुन उवाच
अपरं भवतो जन्म परं जन्म विवस्वतः। कथमेतद् विजानीयां त्वमादौ प्रोक्तवानिति ॥४॥
arjuna uvāca
aparaṁ bhavatō janma paraṁ janma vivasvataḥ। kathamētad vijānīyāṁ tvamādau prōktavāniti ॥4॥
Arjuna asked:
Recent in time is your birth, and remote in antiquity was the birth of Vivasvan. How then am I to understand that you taught it in the beginning?
Gīta Bhāshya 4.04
Arjuna is eager to gain additional understanding of the lord's greatness, which was previously proclaimed in verse 3.30.
It is already said - "In me dedicate all actions" (3.30). To understand the origin of that greatness, Arjuna inquires through "aparam" verse.
Gīta Tātparya 4.04
Those who are wise ask questions to bring unique wisdom to the forefront of society.
"Even though they have previous understanding, the wise ask question about the special knowledge to establish, and to ascertain. Similarly, Arjuna inquired."
From such statements of Agni Purāna, it becomes clear Arjuna is not asking because he doesn't know the Lord.
