PLS HELP. NO LINKS. NO SCAM. What is the purpose of the underlined part of the sentence?

One of Jin's greatest joys in life is sledding down the hill in the park.
A. It is a gerund that names an action.
B. It is a participle that modifies the word hill.
C. It is a participle that modifies the word down.
D. It is a gerund that states who performs an action.