Plant part used as vegetable in Brassica oleracea var. botrytis is
Brassica oleracea var. botrytis is a plant species that includes many common foods as cultivars, including cabbage, broccoli, cauliflower etc. An inflorescence is a group/cluster of flowers arranged on a stem which is composed of the main branch or complicated arrangement of branches. The plant part which is used as a vegetable in Brassica oleracea var. botrytis is unripe inflorescence. So, the correct answer is 'Unripe inflorescence'.