The correct option is B Unisexual
Flowers in the Asteraceae (Sunflower family) are really composed of many tiny flowers called as florets. There are two types of florets: ray florets and disc florets. Disk florets make up the centre of a flower head. They are complete, actinomorphic and bisexual. Ray florets are arranged around the circumference of the central disc called , these are non-reproductive female flowers i.e incomplete, zygomorphic and unisexual.
So, the correct answer is 'unisexual'