Topic: Right Form of Verb,

Best Answer Explained in Below-:

The sentence "I saw Nawshin — skillfully" requires a specific form of the verb that conveys the action performed by Nawshin in a continuous or ongoing manner. Among the options provided:

A) "to ride" is an infinitive form and doesn't align with the structure we need.
B) "riding" is a gerund or present participle form, which indicates an ongoing action and fits contextually with "skillfully."
C) "rode" is the simple past tense, suggesting a completed action rather than a current, skillful performance.
D) "ridden" is the past participle form, typically used with auxiliary verbs and does not work in this context.

Therefore, "riding" is the only option that correctly completes the sentence by implying that I observed Nawshin in the act of riding, and that this action was performed with skill. This use of the present participle encapsulates the notion of an ongoing and active experience, making it the ideal choice for the intended meaning of the sentence.