what kind of bonds join the okazaki fragments
I'm pretty sure the "phosphodiester bond" part is correct.

The only thing I can think of that might be questionable is the word "directly". If directly = immediately, then the sentence could be termed false, because they aren't joined immediately.

Even then, it seems like that's just grasping at straws, so I wouldn't worry too much about it. It sounds like you understand the concept, which is what matters.