Read the passage below and choose one correct answer for each question.

Hue Beef Noodle Soup

If people come to Hue, they will not forget the flavor of "bun bo Hue" - a specialty of Hue. A bowl of noodles with white noodles, pieces of pig's trotters will make unique impression about Hue cuisine.

Whether North, South or Central, “bun” also creates unique and specific dishes in each region. However, in Hue, they like “bun” rather than other ones because of the style of “bun Hue”. Hue style not only is the elegant, sophisticated, precise dishes but also the spirit of the processor. Coming to Hue, either morning or afternoon, walking along the small streets, people can find easily Hue beef noodles. Someone must select the correct address with preferred flavor.

The major ingredients to cook Hue beef noodles are beef and pork. Beef is chosen carefully meanwhile pork would be taken from elbow down to the pig’s feet. They will be boiled for about half an hour. After that, they crush lemongrass and put into the boiling water. “Mam ruoc” will be used with suitable quantity in order to create an attractive scent.

Everyone once tried it, they would be impressive with white noodle, few slices of red chili and green lemongrass. Pieces of pork mixed with beef creates delicious dish. The flavor is felt not only by tasting but also by smelling. In addition, people must enjoy Hue beef noodles with banana flower and white basil. Life changes and it also has some changes. Although, it has some changes, some differences, people cannot forget special dishes in Hue.

What is “mam ruoc” used for?