A IS THE ANS
LET R(A,B,C) AND B IS THE KEY
LET R1==(A,B) AND R2=(B) SO R1 U R2 = R1
DEFINATION OF LOSSLESS D: SAYS THAT IF THE INTERSECTION OF TWO RELATION HAS A COMMON ATTRIBUTE AND THAT IS A KEY IN ANY OF THE RELATION THEN IT IS LOSSLESS
NOW R1 ∩ R2 =B...AND B-->R1(COZ B IS THE KEY) SO LOSSLESS
AND IT CAN ALSO BE STATED THAT
R1 ∩ R2 =B..AND B-->R2 ..SO LOSSLESS
THEREFORE IF WE HAVE ANY ONE OF THE ABOVE THEN IT IS LOSSLESS
SO A IS THE ANS