Cleistogamous flowers
a)	Never open	b)	Always open
c)	Sometimes they open	d)	Remain still

(a)

Never open.

Chasmogamy is the type of autofertilisation (self-fertilisation) in which both male and female gametes present on same flower but pistil and stamen have special adaptation like bending length, etc., so that fertilization takes place. They are open flower not closed like cleistogamous flowers