Answer:
I think its D but I'm not sure.
Explanation:
Just use proccess of elimination
A: Wrong since a reliable source doesnt need to be on the internet.
B: Wrong due to the fact that it can be long however that doesn't mean it's reliable.
C: Wrong since it doesn't need another source to prove it but I'm not sure about this one.
D: Yes because basically reliable means trustworthy.
