English Wikipedia credits Nintendo EPD as the developer of Splatoon Raiders.
Nintendo EPD means Nintendo Entertainment Planning & Development, the company’s internal development division responsible for many major first-party games. The Raiders infobox lists Nintendo EPD as developer and Nintendo as publisher, distinguishing the team that made the game from the company releasing it.
The credit also fits the modern history of the Splatoon series. Nintendo EPD was formed in 2015 through the merger of Nintendo Entertainment Analysis & Development and Nintendo Software Planning & Development. Later Splatoon titles, including Splatoon 2 and Splatoon 3, are associated with this post-merger development structure.
A common mix-up is Nintendo SPD, which was the older Software Planning & Development division and ceased to exist as a separate division after the 2015 reorganization. HAL Laboratory and Monolith Soft are also Nintendo-affiliated development partners, but Wikipedia does not credit either studio as Raiders’ developer. The quiz is asking for the specific infobox credit, not a broad description of Nintendo’s corporate development network.