Final answer:
The correct choice for the phrase 'quickly running' is 'c) Quickly running,' which reflects standard English usage with a space between the adverb and the verb.
Step-by-step explanation:
The question revolves around identifying the correctly written compound word for 'quickly running.' The four options provided are a) Quickley running b) Quickly running c) Quickly running d) Quickley running. Compound words are two or more words combined to create a new word that often has a different meaning than the individual words separately. However, 'quickly running' is not a compound word; rather, it is an adverb ('quickly') followed by a verb ('running'). Therefore, the correctly written phrase is 'c) Quickly running,' with a space between the words, reflecting correct English usage.