Identify the option showing the grammatically correct plural form of the singular noun 'दवाई' (Dawai - Medicine):

According to Hindi grammar rules for number transformation, when a feminine noun ending with a long vowel 'ई' (like दवाई) is converted into its plural form, the long 'ई' shortens to 'इ' and the suffix '-याँ' is attached. Therefore, the accurate spelling is 'दवाइयाँ'.