Question

Flowers are unisexual in.
A. Onion
B. China rose
C. Cucumber
D. Pea

Answer 1

The flowers in which the either male or female reproductive organs are present are called unisexual flowers.That means their flowers are either pistillate or staminate. They need cross pollination for pollinating their flowers.

Complete answer:
When the stamens which is androecium (male) and pistil which is gynoecium (female) are present on different flowers, the flowers is said to be unisexual. Those flowers which only consist of the stamens, that is the male flowers, are also called staminate flowers while those with only pistil present in are known as the female flowers or we can call them, pistillate flowers.
Some examples of unisexual flowers are-

Cucumber
Chrysanthemum
Papaya

So, the correct answer is “Option C”.

Additional information:-
Pollinators that Abiotic pollinators as the name suggests are nonliving agents such as
By wind: Also known as anemophily is probably by insect pollination, which is most common. The pollen is transported more efficiently; wind pollinated plants developed specific heights and stamen and stigma positions for effective dispersal and transfer.
By water: Also known as hydrophily. It carries dry pollen.
Biotic pollination occurs by living organisms:-
By insects: also known as Entomophily, often occurs in plants with colored petals and fragrance to attract insects like, bees, wasps and ants
By vertebrates: such as birds, bats, hummingbirds, sunbirds also known as zoophily. Flowers have colored petals, fragrance and produce nectar.

Note:
For reproduction they have to undergo cross-pollination because they do not consist of both stamen and carpels. Cross pollination requires vectors such as bees and butterflies. Male flowers are unable to produce fruit.