Complete the sentence with the correct part.
A sweating room has a big oven which is filled with stones. A fire heats the stones so ____

• that they become red.
• very important.
• hours in the baths.
• four or five wide steps.
• where they may drink tea and chat.
• a sweating room and lounge.
• become stronger and happier.
• twigs with leaves from trees.
• herbs, leaves and flowers.
• after sweating.