Whilst all the options presented can help improve readability of a worksheet, the best answer is B. Sort and Filter.
When working with very long tables, the sort and filter functions allow table data to be better organised to improve readability. You can sort by a criteria or filter out all data except what you are looking for.
Merge & centre and wrap text relate to text formatting in the cells themselves, these are useful features in general but not essential. Conditional formatting is a useful tool to highlight certain types of data, such as to colour the cell based on its value. Again, it is not as powerful as sort/filter.
