Final answer:
Trends in musical theatre since 1990 include socially relevant stories, blending of musical styles, technological advancements, and increased diversity and representation.
Step-by-step explanation:
The trends that have developed in musical theatre since 1990 include a shift towards socially relevant stories and a blending of different musical styles. Musicals like Assassins and RENT challenged audiences with their themes and narratives. The development of technology also played a role, with advancements in set design, lighting, and sound that allowed for more immersive and visually stunning productions. Additionally, the influence of society and culture can be seen in the increased emphasis on diversity and representation in musical theatre.