Wikimedia Corporation is a licensed corporation engaged in Type 1 regulated activities. Its licensee, Mr To, receives telephone calls from customers.When a customer issues a trading instruction on the phone, which of the following statements is correct?
选项：

A: This call recording is not covered by the record-keeping rules.
B: Mr. Du can only use the landline to 答案 the phone.
C: Mr. Du can 答案 the phone on his mobile phone, but he needs to get prior approval.
D: In any case, the use of mobile phones is prohibited