Most common type of conjoint twin is -

Ans. is 'a' i.e., Thoracopagus o In case of monozygotic twins, the following possibilities may occur:# If the division takes place within 72 hours after fertilization (prior to morula stage) the resulting embryos will have two separate placenta, chorions and amnions (diamniotic - dichorionic twins)# If the division takes place between the 4th and 8th day after the formation of inner cell mass when chorion has already developed - diamniotic monochorionic twins develop.# If the division occurs after 8th day of fertilization, when the amniotic cavity has already formed, a monoamniotic monochorionic twin develops.# On extremely rare occasions, division occurs after 2 weeks of the development of embryonic disc resulting in the formation of conjoined twins, called as Siamese twins.o Four types of fusion may occur:# Thorapagus - Most common# Pyopagus (posterior fusion)# Craniopagus (cephalic)# Ischiopagus (caudal)