Multi-choice problem: Continue writing the next sentence in this paragraph:

How to weatherproof a door
Use adhesive weatherproofing strips.
Before using adhesive weatherproofing products, thoroughly clean the area according to the directions on the weatherstrips. Once the area is dry, remove the backing of the adhesive strips a little at a time as you press them into place on the door jambs and along the edges of the doorframe.

Available options: a). Modern doors are usually designed with grooves along the sides and jambs that weatherstripping can be inserted into. Sometimes it can be difficult to apply an adhesive strip by yourself.. b). Paint the outside of the door red so that it is hard to see through. Lightly tap with a lot of tapping pieces (also known as spatulas) the surface where you will be applying the paint.. c). Make sure your door frames do not stick on the door. As long as they have many of the same protective qualities, the locks on your doors will still be able to stand.. d). Adhesive strips will secure better in drafty spaces than in places that shouldn't be subjected to full sun. Not all paints and finishes will withstand a lack of adhesive..
a).