One cannot cooperate withpeople who aren't interested in teamwork.Here the underlined part is a/an -

• One cannot cooperate with people who aren't interested in teamwork. Here the underlined part is a - Noun clause.
• A noun clause is a group of words that band together and act like a noun.
- Nouns clauses are used when a single word isn't enough.
- They're always dependent clauses.

• একটি বাক্যের চারটি স্থানে Noun clause  বসতে পারে-
1. subject হিসাবে 
2. transitive verb এর object হিসেবে
3. Linking verb এরপরে complement হিসাবে 
4. Preposition এর Object হিসেবে।
- প্রদত্ত বাক্যে ' people who aren't interested in teamwork' clause টি Preposition to এর পর বসাতে এটি Noun clause.