Which words from the paragraph best help the reader understand the meaning of the underlined word?

I was strolling along by the pond in the park when a group of geese strutted out of the water. All of a sudden, I found myself amid these large birds. They gathered around me until I was in the middle of them. A few of them honked, and I was very surprised by how trusting they were. Not wanting to scare them, I stood very still until all of them had waddled past.

A.
of a sudden

B.
surprised by

C.
gathered around

D.
in the middle of