PersonA, You are missing the following items: 'A, B, C, D, E and F.'
PersonB, You are missing the following items: 'A and B'
PersonC, You are missing the following items: 'A'
PersonD, You are missing the following items: 'A, B, C and D'

PersonA, You are missing the following items:
'A,
 B,
 C,
 D,
 E,
 F'