Consider these sentences: I have a new hobby.
I keep track of all the wild birds I spot.
Which sentence uses parenthetical elements most effectively to combine the information in the sentences?
A. I have a new hobby, which is keeping track of all the wild birds I spot.
B. I have a (new) hobby, which is keeping---track of all the (wild) birds I spot.
C. I have a new hobby, keeping track---of all the wild birds I spot.
D. I have a new hobby---keeping track---of all the (wild) birds (I spot).