Answer:
The answer is a).
Step-by-step explanation:
- A topic is mostly used for pieces of writing. They can be easily identified, as they explain what a text is about. Actually, the topic of an essay, article or even a story will usually be stated at the beginning of the text.
- A subject is used for wider areas of knowledge. It's possible for a subject to involve many different topics, but not the other way around.
It may be possible to use the term interchangeably to talk about the important aspects of a document, speech or presentation.