An- unmarried female of 28 years old , has been amenorrhea for 2 years . The size of uterus is normal by anal examination , and progesterone challenge test is negativ
E: The next best examination is :
选项：

A:Pituitary stimulation test
B:Basal body temperature ( BBT )
C:Chromosome examination
D:Hormone determination
E:Estrogen challenge test