The correct option is B United, valvate sepals; free, twisted petals; free stamens; unilocular ovary with basal placentation
The diagram is showing five united sepals (gamosepalous) in valvate aestivation, five free petals in twisted aestivation (petals alternate to each other), five free stamens, unilocular ovary with one ovule. The ovule is attached at the base of the ovary through the placenta. Such placentation is called basal placentation. Thus, the correct answer is 'united, valvate sepals; free, twisted petals; free stamens; unilocular ovary with basal placenta'.