To solve this problem, we need to identify which of the given plants is monoecious. Let's analyze each option:$\newline \bullet$Carica papaya:$\newline$ - Carica papaya is a dioecious plant, meaning it has separate male and female plants.$\newline$ - Therefore, it is not monoecious.$\newline \bullet$Chara:$\newline$ - Chara is a genus of green algae that is monoecious, meaning it has both male and female reproductive structures on the same plant.$\newline$ - Therefore, Chara is monoecious.$\newline \bullet$Marchantia polymorpha:$\newline$ - Marchantia polymorpha is a dioecious liverwort, with separate male and female plants.$\newline$ - Therefore, it is not monoecious.$\newline \bullet$Cycas circinalis:$\newline$ - Cycas circinalis is a dioecious gymnosperm, meaning it has separate male and female plants.$\newline$ - Therefore, it is not monoecious.$\newline$Based on the analysis, the correct answer is Option 2: Chara, which is monoecious.