As type of curve is seen in both tympanosclerosis and otosclerosis
Tymoanosclerosis is a diagnosis that is made on inspection of the TM . No test is required for that .
In the above question the history of B/L progressive, maternal history, aggravating during pregnancy …. All are highly in favour of otosclerosis and that can be confirmed only by Tympanometry.
Choice B is also suggestive … but if we have to choose one , the best answer will be Tympanometry
Otosclerosis shows CHL… And IOC as well as single best investigation for CHL is impedance audiometry… It is a combination of various investigations including tympanometry, stepedial reflex etc
Always rely on OBJECTIVE TEST if available