What statement is accurate and correct?

What statement is accurate and correct?

What statement is accurate and correct?

    Answers:
    A.
    Every Scheme pair is a list.
   
    B.
    There is only one Scheme list that is not a pair.
   
    C.
    There is only one Scheme pair that is not a list.
   
    D.
    Every Scheme list is a pair.

Answer. B.