Selection of subject is often reliant on the artist’s aesthetic. Aesthetic is the perception of what defines beauty, quality, and appreciation. These qualities are all determined by what era someone was born into, what aesthetics one country may have over another, individual philosophy, and even the aesthetics more specific to a gender. Time is very important in deciding what ideals or goals someone has with their piece. Refer to Norman Rockwell who’s art was made in the early 20th century during the depression, world wars, and civil rights movement. Of course his art reflected the time using subjects like soldiers, interracial interactions, and capitalistic icons. Place is important in deciding subject as well because it determines what the subjects and backgrounds will look like and model after. Rockwell was famous for his all-american subject matter depicting american style houses, holidays, clothing, etc. This is different than what an African artist may depict in terms of parallel subjects.
We can immediately reject two of the answers: "ameliaration" and "pejoration" as they mean that something has a better (the first) or a worse (the second) meaning -but this is not the case here.
Now, the trend is: something returned>>income>> income from rent
as you see, it has a more and more specialised meaning - the answer is "specialization"
