I wanted to say that the participle clauses are the most challenging grammar topic for me. On the one hand, my mind tells me to use "is" because "grammar topic" is singular, but on the other hand, I use the plural noun, so I need to use the plural verb.
I am confused by this sentence and looking for help. How can I express this idea? Which sentence is the correct one, if any? And why?
#1 Participle clauses is the most challenging grammar topic for me.
#2: Participle clauses are the most challenging grammar topic for me.
Edited:
Can I use the plural subject and the singular object? Or maybe, do I need to change the object to plural?