Which is a major concern of Modernist novels?

a) A character's inner thoughts

b) A well-crafted plot

c) A detailed setting

d) An open-ended theme

Modernism came to be due to the massive changes the world experienced after many gruesome events, including both World Wars. Because of this, people entered a reflective stage where they started to dig deep to find out how to live from then on This gave birth to a new focus on emotions, where writers focused on exploring the deepest sentiments and thoughts in society and individuals.

Therefore, your best answer is option A.