己知0.1mol/LNaHCO₃溶液显碱性，将此溶液加水稀释后，下列说法正确的是（ ）

A．稀释后，溶液中各离子浓度均变小。

B．原溶液中，C（Na⁺）= C(HCO₃^-) + C(H₂CO₃) = 0.1mol/L

C．稀释后，溶液中C（Na⁺）/ C(HCO₃^-)比值增大

D．原溶液加入少量NaOH溶液后，其碱性减弱。

Woman: Listen to me, Joe. The exam is already a thing of the past. Just forget about it.
Man: That’s easier said than done.
Question: What can we infer from the conversation().

A. The exam was easier than the previous one.

B. Joe is sure that he will do better in the next exam.

C. Joe probably failed in the exam.

D. The oral part of the exam was easier than the written part.