Which is the best speculation here? Or what would you offer as a better guess?

Question

FINDINGS

Kex I (1-10): -A3D6, -A5F2, -B1C5, -B3B6, -B5F1, -B6E4, -D2D5, -D3E2, -D6E3; +C3C4

SPECULATIONS

"Findings repeat"
"+X9X9"
"-X9X9"
"-X9Y8"
"+X9Y8"
"A's, B's, and C's are alike, i.e., +A9A8, +A9B9, +A9C9, +B9B8, +B9C9, +C9C8"
"Jack's Hypothesis: -A9D9"
"Hayes' Guess: +B2C2"

Best Answer will be selected on strict criteria.

Answer 1

I've never been more confused in my life
no really
sorry

Answer 2

Jack's Hypothesis: -A9D9