Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 18 to 22.

Virtual singers are a novel trend in the field of music. These singers are not human; rather they are generated by artificial intelligence (AI) algorithms, (18) _______. These virtual singers can play music and sing with the same proficiency as human singers. Ann, the first virtual singer produced in Việt Nam by BoBo Studio, (19) _______. Her voice is created using natural human sounds, such as breathing, which makes her sound as real as possible. The entire process is accomplished using complex AI algorithms and sound effects. Ann's first song, "Làm Sao Nói Thương Anh" (How to Say I Love You), was released on YouTube, which is likely to make her an Internet sensation in Việt Nam. The music video is entirely computer-generated using visual effects, which represents a new genre of music. Hoping that she will become a successful ballad singer with a unique musical style that will evolve from ballads to rock with a baby voice, (20) _______.
Virtual singers, like Ann, are not just limited to singing. They can also act, promote fashion and commerce, and are a perfect example of talented AI-generated individuals who can become pop idols. (21) _______.
Countries like Japan, South Korea, and the US have been using virtual singers for a while now. Studios report that virtual singers have some advantages over real singers. For example, virtual singers do not get tired and do not age, which makes them easier to manage and maintain for a longer time. (22) _______.