"Today is Monday" is not the opposite of "Today is Tuesday".i.e. they can both be false.  "Today is Monday" is the direct opposite of "Today is not Monday". One must be true and the other must be false. 
One day, Pip asks his parents: "What day is it today?"  His mother says: "Today is Monday."  His father says: "Today is Tuesday."  From the options below, \textbf{Pip agrees with B}. Do you agree with Pip? 
Options:
1: One of these two sentences is definitely wrong and the other one is correct. 
2: It is possible that both of Pip\textquotesingle s parents are wrong. 
3: It is possible that both of Pip\textquotesingle s parents are right. 
4: If Pip\textquotesingle s mother is wrong, then his father must be right. 