The nurse is planning care for a female client diagnosed with acute hepatitis A virus (HAV). What’s the primary mode of transmission for HAV

A. Fecal contamination and oral ingestion.
B. Exposure to contaminated blood.
C. Sexual activity with an infected partner.
D. Sharing a contaminated needle or syring

在SQL的SELECT语句进行分组计算查询时，可以使用______子句来去掉不满足条件的分组。