The correct option is C All of the above
Elongated cluster of unisexual flowers bearing scaly bracts and lacking petals is known as catkin inflorescence. Catkin (Ament) is a compact pendent unisexual spike in which peduncle is thin and weak. e.g., Morus (Mulberry), Populus (Poplar), Acalypha (Cats tail ), Salix (Willow), Betula (Birch).