Relational algebra is indeed a procedural language. This means it specifies a sequence of operations that must be performed in a specific order to achieve the desired result. It's like providing a recipe for manipulating data within a database.
Why not the others?
Domain relational calculus and tuple relational calculus are declarative languages. They specify what data is desired without specifying how to compute it.
Query language is a broad term that can encompass both procedural and non-procedural languages.
Key point: Relational algebra provides a step-by-step approach to manipulating data, making it a procedural language.