单选题：Two spam mail detection systems are tested on a dataset with 798
Two spam mail detection systems are tested on a dataset with 7981 ordinary mails and 2019 spam mails. System A detects 200 ordinary mails and 1800 spam mails, and system B detects 160 ordinary mails and 1500 spam mails. If our primary concern is to keep the important mails safe, which of the following is correct? @[C](3)
A. Precision is our primary concern and system A is better.
B. Recall is our primary concern and system B is better.
C. Precision is our primary concern and system B is better.
D. Recall is our primary concern and system A is better.
A.Precision is our primary concern and system A is better.
B.Recall is our primary concern and system B is better.
C.Precision is our primary concern and system B is better.
D.Recall is our primary concern and system A is better.
答案：C
A. Precision is our primary concern and system A is better.
B. Recall is our primary concern and system B is better.
C. Precision is our primary concern and system B is better.
D. Recall is our primary concern and system A is better.
A.Precision is our primary concern and system A is better.
B.Recall is our primary concern and system B is better.
C.Precision is our primary concern and system B is better.
D.Recall is our primary concern and system A is better.
答案：C