Final answer:
All three options, 'mending,' 'repairing,' and 'fixing' are correct for the sentence 'Dad was up the ladder, ____ the roof.' However, each word carries a slightly different tone or implies a different extent of work.
Step-by-step explanation:
Dad was up the ladder, mending the roof. In this context, mending, repairing, and fixing are all verbs that could be used to describe the action of fixing something that is broken or damaged. The difference between them is mostly in connotation and common usage. 'Mending' generally has a slightly old-fashioned or informal tone. 'Repairing' is more formal and tends to imply a more comprehensive process, and 'fixing' is a more general term that can apply to any sort of repair no matter how large or small.