Which of the following drug is an aromatase inhibitor?

Letrozole is a third generation aromatase inhibitor which is used as an adjuvant hormonal therapy in postmenopausal women with early stage breast cancer and as a treatment for advanced breast cancer. Aromatase inhibitors blocks the aromatase enzyme involved in the conversion of androgens to estrogens. The most common treatment related adverse events are hot flashes, nausea, and hair thinning. It was also found to cause osteoporosis in patients on it. Tamoxifen, Raloxifen and Toremifene are Selective Estrogen Receptor Modulators. They act by producing beneficial estrogenic action on bone, brain and liver during post menopausal hormone therapy but has antagonistic activity in tissues such as breast and endometrium. Ref: Moy B, Lee RJ, Smith M. Chapter 63. Natural Products in Cancer Chemotherapy: Hormones and Related Agents. In: Brunton LL, Chabner BA, Knollmann BC, eds. Goodman & Gilman's The Pharmacological Basis of Therapeutics. 12th ed. New York: McGraw-Hill; 2011. Accessed August 12, 2013.