Ans. is 'a' i.e. Ethyl alcohol The fixative used to prevent air drying in case of Pap smear is ethyl alcohol.Ordinarily when a slide is prepared it is air dried but when a slide prepared for pap smear is air dried it gets damaged.''Thus while preparing Pap smear slide ethanol is used as a fixative to prevent air drying".Procedure:-The techniques of collection of a pap smear may vary but the following is a common procedure.The patient should not have douched for at least 24 hours before the examination and should not be menstruating.The speculum is placed in the vagina after being lubricated with water only.With the cervix exposed, either a cotton-tipped applicator slightly dampened with saline solution or a specially designed plastic or wooden spatula is applied to the cervix and rotated 360 degrees to abrade the surface slightly and to pick up cells from the squamocolumnar area of the cervical os.Care should be taken to ascertain that endocervical cells are also obtained.If this is not accomplished with the spatula, a cotton tipped applicator or small brush is now available for this purpose, it can be inserted into the cervical canal of most of the women and rotated picking up cervical cells more efficiently.These 2 specimens may be mixed or put on the slide, separately according to the preference of the examiner.A preservative is applied immediately to prevent air drying, which will compromise the interpretation.The preservative or the fixative used is 95% ethyl alcohol (Note: To prevent the air drying, slide is transported in the bottle containing the fixative).