Give E$/$R Diagram. At a birth, there is one baby $($twins would be represented by

two births$),$ one mother, any number of nurses, and any number of doctors. Suppose, therefore,

that we have entity sets Babies, Mothers, Nurses, and Doctors. Suppose we also use a relationship

Births, which connects these four entity sets. Note that a tuple of the relationship set for Births

has the form of

$($baby$,$ mother, nurse, doctor$).$

If there is more than one nurse and$/$or doctor attending a birth, then there will be several tuples

with the same baby and mother, one for each combination of nurse and doctor.

There are certain assumptions that we might wish to incorporate into our design. For each,

tell how to add arrows or other elements to the E$/$R diagram in order to express the assumption.

a$)$ For every baby, there is a unique mother.

b$)$ For every combination of a baby, nurse, and doctor, there is a unique mother.

c$)$ For every combination of a baby and a mother there is a unique doctor.