ROLLY
If 0, 2nd letter is A. Only difference from RALLY - 1
Also last letter is R
RADAR has 2. One is from the second A
R is excluded from ROLLY
A is right
D can't be right because MADAM - 1 (and the 1 comes from the A)
A cannot be right because MADAM - 1 (and the 1 is from the first A)