A: The procedure of marriage, that is, the formal requirements of marriage, is the legal procedure that both men and women must perform when they conclude marriage. In addition to the substantive requirements of marriage stipulated by law, both parties to marriage must also meet certain formal requirements. Only when the marriage formalities stipulated by law are fulfilled can marriage have legal effect and be recognized by the state and society. At present, there are three main forms of marriage procedures in various countries: (1) ritual system, that is, marriage requires a certain ceremony, and the wedding ceremony is the legal requirement of marriage. Marriage ceremonies can be divided into religious ceremonies presided over by clergy in church, secular ceremonies presided over by parents with witnesses and legal ceremonies presided over by government officials. Some countries stipulate that religious ceremonies and legal ceremonies have the same effect, which can be chosen by the parties themselves and recognized by law. (2) The registration system means that marriage must be registered with the legal registration authority, and marriage registration is the legal requirement of marriage. (3) The combination of registration and ceremony means that marriage must be registered and celebrated. Marriage registration and ceremony are dual legal requirements of marriage, and both are indispensable. Article 8 of the Marriage Law stipulates: "If both men and women want to get married, they must register their marriage in the marriage registration office in person. Those who meet the requirements of this law shall be registered and issued a marriage certificate. Getting a marriage certificate is tantamount to establishing a relationship between husband and wife. If you are not registered for marriage, you should re-register. " It can be seen that China implements marriage registration, and both men and women must perform marriage registration procedures when concluding marriage. Marriage registration is the legal procedure for the establishment of marriage in China and the only formal requirement for the establishment of legal marriage. After marriage registration and obtaining a marriage certificate, both men and women have the legal relationship of husband and wife, whether they live together or not, whether they hold a wedding ceremony or not. Their marriage is recognized by the state and protected by law. On the other hand, if a man and a woman only hold a marriage ceremony or live together without registering their marriage, then their marriage has no legal effect. Therefore, option A is the correct option.