Read the following passage and mark the letter A, B, C, or D to indicate the answer to each of the questions.

Japanese Girls' Day-also known as the Doll's Festival-is celebrated on March 3 to pray for the health and happiness of young girls in Japan. Hinamatsuri, the name of the celebration in Japan, is marked by families displaying a set of hina dolls in the house and serving special delicacies that are ceremonially beautiful and delicious.

Traditionally, parents or grandparents of a newborn girl buy a set of hina dolls for the baby, unless they have special dolls that are inherited from generation to generation. From the end of February to March 3, hina dolls dressed in Japanese ancient costumes are displayed on tiered platforms that are covered with a red carpet. The costumed dolls represent the imperial court of the Heian period (A.D. 794 to 1185] and feature the emperor, empress, attendants, and musicians dressed in traditional garb.

The dolls are displayed hierarchically with the emperor and empress at the top, which are set in front of a gilded screen representing the thrown. The number of dolls and their size vary from home to home, but five to seven platforms are common.

It is customary to put the dolls away as soon as the festival is over-there is a superstition that if the dolls are left out, a family will have trouble marrying off their daughters. After the festival, some people release paper dolls into the rivers praying that this will send away sickness and bad fortune.

What does the word "this" in the last paragraph refer to?