PCAP Object-Oriented Programming Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  append: Adds an element to the end of the list.

  Why this is correct

  append() treats its argument as a single object, inserting that object as one new element at the end of the list. Even if the argument is itself a list, tuple, or other container, the list's length increases by exactly one. This method mutates the list in place, so it returns None rather than constructing a new list.

• ✓

  extend: Extends the list by appending elements from an iterable.

  Why this is correct

  extend() fetches each item from the supplied iterable and appends those items individually, so the list grows by the number of elements in the iterable. It is essentially the in-place version of list concatenation for iterables, and when given a string it will add each character as a separate element. Because it mutates the original list and returns None, it should not be confused with the + operator, which creates a new list.

• ✓

  remove: Removes the first occurrence of a specified value.

  Why this is correct

  remove() locates the first element whose value compares equal to the argument by testing each element with __eq__ and shifts all later elements left to close the gap. If no matching value exists, it raises ValueError to signal the failed search. This operation scans from index 0, so it is O(n) and only deletes a single occurrence, even if duplicates are present.

• ✗

  pop: Removes the first occurrence of a specified value.

  Why it's wrong here

  This description is wrong because pop() removes and returns an element by position, not by value. Calling pop() with no argument pops the last element, and pop(i) removes the element at index i, supplying no search semantics at all. To delete the first occurrence of a value, a user must call remove(); pop() would require first finding the index with index() and then calling pop(index).

• ✗

  sort: Sorts the list in descending order.

  Why it's wrong here

  This description is incorrect because sort() defaults to ascending order, placing the smallest element first. Descending order requires explicitly passing reverse=True, as in lst.sort(reverse=True), which then reorders the sequence in place. Additionally, sort() is stable, meaning equal elements keep their original relative order, and it does not return a new list; sorted(), by contrast, returns a new sorted list.

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