そういうことか

The phrase is a combination of: * **そう (sou)**: An adverb meaning "such," "so," "that way." It refers back to something previously mentioned or understood. * **いう (iu)**: The plain form of the verb "to say" or "to be called." In this context, it functions to describe or refer to something. * **こと (koto)**: A nominalizer, turning the preceding phrase into a concept or abstract thing. It can be translated as "thing," "matter," or "fact." * **か (ka)**: A particle that indicates a question, or in this context, often a rhetorical question or an expression of realization/understanding. Literally, it can be broken down as "Is that the thing that is said (to be) so?" or "Is that such a thing?" Over time, this evolved into a common idiomatic expression to convey understanding, realization, or sometimes a hint of resignation or acceptance. It's a very common and natural way to acknowledge new information in Japanese.