Correct Option (c)
Reason : Bisexual flowers which remains always closed are called cleistogamous and such condition of flowers is called cleistogamy. In such flowers, the anthers and stigma lie close to each other. When anthers dehisces in the flowers buds, pollen grains come in contact with stigma to affect pollination. Thus, cleistogamous flowers are invariably autogamous.
Correct Option (c) Reason : Bisexual flowers which remains always closed are called cleistogamous and such condition of flowers is called cleistogamy. In such flowers, the anthers and stigma lie close to each other. When anthers dehisces in the flowers buds, pollen grains come in contact with stigma to affect pollination. Thus, cleistogamous flowers are invariably autogamous.