This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sexual offences and infanticide, Subject name: Forensic Medicine
Twin pregnancy, but due to two different men cause is - 
Select and explain. 
A. Superfactation, B. Superfecundation, C. Both of the above, D. Not A realistic situation
C: Both of the above
Answer: C: Both of the above 
Explanation: Ref:Synopsis of Forensic medicine and toxicology (K.S.Narayan Reddy) 28th edition, page no.208 Superfactation or Superfecundation means the feilisation of two ova which have been discharged from the ovary at the same period, by two separate acts of coitus commited at sho intervals. The incidence of twin pregnancies is about one-and-half percent and of these, about 70% are binovular twins resulting from separate feilisation of two ova formed in the same menustral cycle.