Question

Which of the following is not an unisexual flower?
a) Coconut b) Papaya c) Gulmohor d) Maize

Answer 1

gulmohor is both stamen and carpel in single flower it is bisexul
so your answer is gulmohor

Answer 2

The answer is © Gumohor. It is not a unisexual flower, it is a bisexual flower.

According to definition of bi-sexual flowers the flower which contains both the stamens and the pistil are known as bisexual flowers.  

If we close view a Gulmohar flower, it will be seen that it contains both stamens and pistils, and that is why it is tagged in bisexual flower category.