Let's evaluate each statement:

I – Even though technology has had a great part in the 20th-century history, the main feature of this period is the beginning of post-modernity.

- This statement discusses the relationship between technology and the 20th century, but it doesn't directly address technology's role in literature. It focuses more on historical aspects.

II – In Literature, technology may represent power and the necessity of a great development process of humanity.

- This statement connects technology to literature, suggesting that technology can symbolize power and the need for human development in literary works.

III – Technology is part of the 20th and 21st-century literary aesthetics.

- This statement directly relates technology to literary aesthetics in the 20th and 21st centuries.

Considering the context of the question and the focus on technology's role in literature, statement II is the one that directly addresses this relationship. Therefore, the correct answer is:

(C) Just II is correct.

While statements I and III may have relevance in a broader discussion, they don't directly address the role of technology in literature as statement II does.