Layla and Kayla are twins who were separated at the birth. A researcher interested in studying heredity tracks them down and speaks to their dissimilar families regarding the benefits which can be accomplished by studying two young girls. The girls and their dissimilar sets of parents agree to participate, and studies begin assessing different areas of girls' lives. In order for this type of twin study to be most effectual, what kind of twins should Kayla and Layla be?
a. conjoined
b. monozygotic
c. amorphous
d. dizygotic