Explanation:
The word 'valuable' means something that is of great worth, importance, or usefulness. It is used to describe something that is highly prized and has a high monetary or sentimental value.

Invaluable:
The word 'invaluable' is the opposite of 'valuable'. It means something that is so precious that its value cannot be measured. For example, the love of a mother or the support of a friend is invaluable.

Worthless:
The word 'worthless' means something that has no value or importance. It is used to describe something that is of no use or benefit. For example, a broken pencil or a torn piece of paper is worthless.

Inferior:
The word 'inferior' means something that is of lower quality or standard. It is used to describe something that is not as good as something else. For example, an inferior product is one that is of lower quality than its competitors.

Lowly:
The word 'lowly' means something that is humble or insignificant. It is used to describe something that is not important or of a lowly position. For example, a lowly clerk is someone who works in a low-level position in an office.

Conclusion:
Out of the given options, the correct answer is 'worthless' as it is the opposite of 'valuable' and means something that has no value or importance.