单项选择题

The effective temperature of air is dependent upon_______.Ⅰ.relative humidity Ⅱair velocity
A.Ⅰonly
B.Ⅱonly
C.Both Ⅰand Ⅱ
D.NeitherⅠnor Ⅱ

A.Ⅰ.relative
B.Ⅰonly
B.Ⅱonly
C.Both
C.NeitherⅠnor