Read the following passage about AI-generated virtual singers 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, ___(1)___. These virtual singers can play music and sing with the same proficiency as human singers.
Ann, the first virtual singer produced in Viet Nam by BoBo Studio, is a remarkable example of this technology. Her voice is created using natural human sounds, such as breathing, which makes her sound as real as possible. ___(2)___.
Ann's first song, "Làm Sao Nói Thương Anh" (How to Say I Love You), was released on YouTube, ___(3)___. The music video is entirely computer-generated using visual effects, which represents a new genre of music. Ann's creators hope that she will become a successful ballad singer, with a unique musical style that will evolve from ballads to rock with a baby voice. They aspire for Ann to become a popular idol, renowned for her musical talents.
___(4)___. They can also act, promote fashion and commerce, and are a perfect example of talented AI-generated individuals who can become pop idols.
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, ___(5)___, which makes them easier to manage and maintain for a longer time.
(Adapted from English Discovery)