Which one is monoecious? A. Marchantia B. PinusC. CycasD. Papaya

The correct option for a plant that is monoecious is B. Pinus. Pinus is a genus of coniferous trees that includes species such as pines. Monoecious plants have separate male and female reproductive structures on the same plant. In the case of Pinus, male cones produce pollen while female cones produce seeds, both on the same tree. The other options you provided are not monoecious. Marchantia is a liverwort and can be either dioecious (separate male and female plants) or monoecious. Cycas is a gymnosperm that can be either dioecious or monoecious, depending on the species. Papaya is a flowering plant that is dioecious, meaning it has separate male and female plants.