Which are two MPLS label discovery Mechanisms?

Out of below options which two are correct label discovery mechanisms:-

1. Targetted
2. Standard
3. Strict
4. Basic 
5. Extended 

Answer:- Option 4 and 5 are correct.

Basic discovery is also known as Directly Connected MPLS LDP Sessions where LDP peers are directly connected

Extended Discovery is known as inDirectly Connected MPLS LDP Sessions where LDP peers are not directly connected.