What is the primary distinction of Ginjo-shu compared to other sake types?

Ginjo-shu is distinguished primarily by its quality level, which is classified as premium or superpremium. This classification is linked to the meticulous brewing process and the careful selection of ingredients, specifically the rice used in production. The rice for Ginjo-shu is polished to at least 60% of its original size, meaning that 40% of the outer layer is removed, leading to a more refined and nuanced flavor profile.

In contrast to other sake types, which may not require such high-polished rice or stringent brewing practices, Ginjo-shu undergoes fermentation at lower temperatures, allowing for the development of delicate aromas and flavors that characterize its premium status. Therefore, the quality aspect is a core defining feature of Ginjo-shu, making option B the correct response.

The other choices do not accurately describe Ginjo-shu: it is not exclusively produced using machine processes, nor is it confined to a specific region in Japan, as it can be made throughout the country. Additionally, it is generally priced higher than standard types of sake, given its higher quality and production standards, contrary to being cheaper.