问题如下：
Which of the following is correct when modeling risk frequency?
选项：
A. It usually uses a Poisson distribution.
B. Time-weighted loss number is used when calculating frequency
C. It usually assumes that risks are highly correlated through time to time.
D. It usually assumes risk frequency and severity are highly correlated.
解释：
A is correct.
考点：risk frequency and severity
解析：计算风险频率时一般使用泊松分布，通过调节λ来完善损失数据的准确性。
老师，想问B和C错在哪里呢
