Which Statement Most Accurately Describes Iwan Bloch's Contribution to Our

Which statement most accurately describes Iwan Bloch's contribution to our understanding of sexual behavior?

A) Bloch carried out the first laboratory study of human sexual response.
B) Bloch conducted the first scientific survey about then-current sexual practices.
C) Bloch was the first to apply a historical approach to understanding sexual behavior.
D) Bloch was the first to recognize that sexual problems were often at the root of mental illnesses.