a . is correct. A gerund, by definition, is a form of a verb used as a noun.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
WowenglishI wonder if "1" and "2" have the same meaning.No! What you need, if you want the same meaning, are these:
1. Recently I encountered a cab driver helping me with books and parcels.
2. Recently I encountered a cab driver who helped me with books and parcels.