The correct option is C Placenta
The tissue which attaches the ovules inside the ovary is placenta. In flowering plants, placentation occurs where the ovules are attached inside the ovary. The ovules inside a flower's ovary are attached via funiculi, the plant part equivalent to an umbilical cord. The part of the ovary where the funiculus attaches is referred to as the placenta.
Therefore, the correct answer is option C.