Given Alice has signed Bob's key, and Bob has signed Chloe's key, Alice would like to send Chloe a secure e-mail using Chloe's key but Alice cannot check Chloe's key physically. Instead Alice could rely on Bob's key to check Chloe's key validity. Now for Chloe's key to be validated by Alice, it should fulfill two conditions :
1- It has been signed by one fully trusted key, or it has been signed by three marginally trusted keys; 2- There is at most five hops between Alice and Chloe.
My question concerns condition 1 : Does Bob's key have to be the one to be fully trusted by Alice or does Chloe's key have to be the one to be fully trusted by Bob or both ?
P.S. I have based my understanding of PGP trust model on this link