Foreign speakers learning english often use dangling modifiers.
a. true
b. false

Hm, I don't think that there is one certain answer, but here is some information to go on:

1) Native speakers often use dangling modifiers themselves - why should the learners  not do it?

2) this would depend on their original language. If it has a similar structure, then yes, they would likely used them.

In total I would prefer a)