why px 2 excluded leh?

PAX6
A === 4 months
B ===
C+ (C1)=== 2.25
C (C2)===
C- (C3) ===


PAX5
A ===
B+ ===
B ===
C+ === 2.75 months
C ===


PAX4
A ===
B+ === 3.75 months
B ===
C+ ===
C ===

PAX3
A ===
B+ ===
B ===
C+ ===
C ===