The newly fertilized egg gains mass only after it is implanted in the uterus wall. Before the implantation, there is no gain in the mass of the fertilized egg. Moreover, the nourishment is not derived from the cell of the uterus. A newly fertilized egg is capable of surviving without the nourishment from mother as long as the nourishment is provided in vitro. Hence, the statements of Nina and Carole are not right.
Hence, the answer is 'the statement of Sarah is correct'.