Exercise 3 (Relational Algebra) (22 points] Consider the following relations. The primary keys are underlined. All attributes are of type string if not indicated otherwise. Suppliers (SID, sname, address) Parts (pID, pname, color) Catalog (sID, PID, cost: integer) 1. [6 points) Find the names of the most expensive parts supplied by supplier named 'NESCS'. 2. [4 points) Find the names of the parts supplied by at least two different suppliers 3. [4 points) Find the ids of suppliers who supply every red part or supply every green part. 4. [4 points) Find pairs of supplier ids such that the supplier with the first sID charges more for the same part than the supplier with the second sID. 5. [4 points) Find the names of suppliers who supply only red parts