The correct option is
B A head inflorescence
A capitulum or head, is the characteristic inflorescence of the sunflower family (Asteraceae). In this type of inflorescence the main axis or receptacle becomes suppressed, and almost flat, and the flowers (also known as florets) are sessile (without stalk) so that they become crowded together on the flat surface of the receptacle. The heads can be made up of combinations of ray and disk florets. Ray flowers have a strap-like petal while disk flowers are tubular. Ray florets are usually larger and showier than disk florets but each can have both male and female parts. In a mixed head of ray and disk florets, the outer ray florets are usually sterile or female only.