Fill in the blank with the comparative form of the adverb:
Jim threw the ball ______ than Peter.

The hint of Positive Degree is ‘as…as/so…as.’ The hint of Comparative Degree is ‘than’. The hint of Superlative Degree is ‘the. the shape of an adjective or adverb word is modified such as: (Positive- Strong)/ (Comparative- Stronger) / (Superlative-Strongest). During transformation, the first meaning of the sentence is modified. During transformation, so as to stay the meaning the identical, the position of subject and object is modified.
Option a ‘Farther’ is that the correct option because it shows a comparison between two proper nouns and properly follows the structure of the degree of comparison.
Option b ‘Far’ indicates the positive degree of comparison and hence isn't the proper option because the sentence demands the comparative degree.

Option c ‘Farthest’ is that the superlative degree of comparison and hence isn't the proper option.
Option d ‘Fur’ is all at once may be a different word with a special meaning that doesn't suit the sentence. It means the soft hair of animals. It doesn't provide any coherent assuming to the meaning and is neither an adjective nor an adverb. So, this feature is wrong.

Note: The question itself hints at the proper answer by the presence of ‘than’.