The correct option is A Cyathium
A. Capitulum or head in which the main axis becomes flat and called receptacle. It bears many sessile and small florets. It is a type of racemose inflorescence. The example is a sunflower.
B. Cymose in which the main axis terminates into a flower and hence has limited growth. The flowers are arranged in a basipetal order. The example is teak.
C. Cyathium looks like a single flower. A cup-shaped involucre formed by bracts encloses a single female flower and a number of male flowers. The example is euphorbia.
D. Corymb in which the main axis is short. Lower flowers have long pedicles than upper ones so that all the flowers are brought more or less to the same level. It is a type of racemose inflorescence. The example is iberis.
So, the correct answer is 'cyathium'.