The correct option is
C Sessile flowers
A. Raceme in which peduncle has bisexual and pedicellate flowers arranged in acropetally. It is a type of racemose inflorescence. The example is a radish.
B. The complete arrangement of flowers on the floral axis of the plant is called an inflorescence. It is of two major types - racemose and cymose.
C. Spike in which peduncle has bisexual and sessile flowers. It is a type of racemose inflorescence. The example is Achyranthes.
D. Catkin is a pendulous spike in leaf axis which bears unisexual flowers. It is a type of racemose inflorescence. The example is oak.
So, the correct answer is 'Sessile flowers'.