Which early Nirvana trait best defined their Sub Pop era sound?

Sub Pop Underground Era (1987-1990) poll options

Sub Pop Underground Era (1987-1990)

Nirvana: Formation to Sub Pop Records Era (1987-1990)

Nirvana

• Cobain's raw, wounded vocals
• The sludge-heavy guitar attack
• The punk-meets-pop songwriting
• The chaotic underground energy