Which of the following shall be a compound proposition involving the propositions p, q and r, that is true when exactly two of the p, q and r are true and is false otherwise?

• A. (p ? q ?? r) ? ( p ? q ? r) ? (? p ? q ? r)
• B. (p ? q ? r) ? ( p ? q ? r) ? (? q ?? p?? r)
• C. (p ? q ?? r) ? ( p ?? q ? r) ? (? p ? q ? r)
• D. (p ? r ? q) ? ( p ? q ? r) ? (? p ? q ? r)