An array keeps an ordered sequence of values. Choosing the right operation means deciding whether you need a slice, a changed copy, an ordering, or an all-items condition. slice excludes its end index and doesn't remove entries from the source. sort changes its array and compares strings unless you supply a numeric comparator. Copy first when the caller needs the original list later. The same requirement applies to replacing one slot: a second variable can point at the same array rather than a new one. These exercises make both versions visible so you can check the copy behavior. Include an empty array in your reasoning, especially when using every.