Correct option is C
In reproductive age women (30–40 years), breast cancer is the most common malignancy in India, making it the leading cancer in this age group.
Explanation of options: (a) ✘ Cervical cancer incidence peaks later (40–50 years). (b) ✘ Ovarian cancer is less frequent compared to breast cancer at this age. (c) ✔ Correct; breast cancer is most common among women aged 35 years in India. (d) ✘ Thyroid cancer is seen but not the leading cancer.