A. An inflorescence is the arrangement of flowers on the floral axis of the plant. Two major types of the inflorescence are - 1. Racemose - the shoot axis continues to grow indefinitely and the flowers are borne in acropetal succession. Examples are radish, Lupin, and mustard. 2. Cymose - the main axis terminates into a flower and has a limited growth and the flowers are borne in a basipetal order. Examples are begonia, teak, and Solanum.
B. Phyllotaxy is the pattern in which the leaves are arranged on the stem or its branches. The leaves are arranged in three ways - 1. Alternate - single leaf is present at each node in the alternate fashion. Examples are China rose, mustard, and sunflower. 2. Opposite - a pair of leaves arise at each node on the opposite side, the leaves lie opposite to each other at each node. Examples are guava and calotropis. 3. Whorled - more than two leaves arise at each node and form a whorl or a circle, the leaves of one whorl alternate the leaves of the next successive whorl so that all the leaves receive maximum sunlight. Examples are Alstonia and Nerium.
C. Placentation is the arrangement of ovules on placenta within the ovary. It is of six types- marginal, axile, parietal, free central and basal.
D. A corymb is lower flowers have long pedicels than upper ones so that all the flowers are brought more or less to the same level. The main axis is short. Examples are Iberis and Capsella.
So, the correct answer is 'inflorescence'.