A) If your choice is between doors and the curtains, then solid tightly closed doors will be a better option. This is especially true if you are dealing with two rooms such as a living room and family room (where appearance and convenience also counts).
But — the curtains will do the job too. You can install the curtains tightly, with no cracks between the curtains and the walls. The curtains come in 48 inch width. Â If your doorway is 63 inches, you would need two curtains (48 x 85 inches each) so they can overlap each over and can be installed above the door frame.