What is the most likely diagnosis?

A 17-year-old Caucasian girl presented with primary amenorrhea.

On examination, her body mass index was 21 kg/m2 (18C25). Her body habitus was normal and she had appropriate breast development. There was no hirsutism or acne.

Investigations:

serum oestradiol<180 pmol/L (200C400)

serum testosterone31.7 nmol/L (0.5C3.0)

serum follicle-stimulating hormone4.0 U/L (2.5C10.0)

serum luteinising hormone6.0 U/L (2.5C10.0)

What is the most likely diagnosis?
A . adrenocortical carcinoma
B . androgen-secreting ovarian tumour
C . complete androgen insensitivity syndrome
D . ovarian hyperthecosis
E . polycystic ovary syndrome