The figure shows the female reproductive tract with four places marked P, Q, R and S. Where is the zygote placed in ZIFT?

Fig. 1: A front view of the female reproductive tract: the uterus, two fallopian tubes, two ovaries and the vagina. Four letters with arrows: P points at the vagina, Q points at the cavity of the uterus, R points at a fallopian tube, and S points at an ovary.