The one which has both unisexual and the bisexual flowers on the same plant is the answer of this question i.e., the presence of male, female and bisexual flowers on the same plant.
First of all, what is polygamous plant. As the name indicates, poly means many and gamous means having reproductive organs. So, the polygamous plants are the flowering plants which have both unisexual (male, female) and bisexual flowers on the same plant. In other words, a plant may have both bisexual and male flowers or bisexual and female flowers. Some may have bisexual, male and female flowers.
If we look at the option A i.e., Mango. Mango is a polygamous plant because mango contains both the bisexual and male flowers. Bisexual flowers means those flowers which have both the stamens and carpels, it also increases the chance of cross pollination.
Moving to option B i.e., Pink flower. Pink flower is not an example of polygamous plant since it has only unisexual flowers on the same plants. Therefore, this option gets eliminated.
Next option is option C i.e., Rose. It is also not an example of polygamous plant because it also have both male and female part but it does not have bisexual flowers. This option also gets eliminated.
Now the last option is D i.e., Gossypium. It is commonly known as cotton. These are also not polygamous plant since it has unisexual flowers only. This option also gets eliminated. From all the above options it is clear that mango is the only polygamous plant from the given options.
Thus, the correct answer is option A i.e., Mango.
Note: When there are male, female and bisexual flowers on the same plants then it is termed as polygamous plant. Mango is an example of this plant. Male and female flowers are on the same tree in mango and their flowers are small and white with five petals and these are produced in terminal panicles.