In the following question on one-word substitutions, select the word that best means “lack of skill, ability, or competence”.

Introduction / Context:
This is a one word substitution question that tests your ability to match a given definition with the correct English noun. The phrase given is lack of skill, ability, or competence. The correct one word substitution must capture the idea of poor ability or clumsiness, not high skill.

Given Data / Assumptions:
• The definition is lack of skill, ability, or competence.• The options are ineptitude, dexterity, proficiency and prowess.• We assume that the correct answer will describe a negative state of incompetence.

Concept / Approach:
Ineptitude is a noun that means clumsiness, incompetence or the quality of being inept. It directly expresses lack of skill. The other three options all describe positive qualities: dexterity means skill and agility, especially with the hands; proficiency means a high degree of competence or skill; and prowess refers to great skill or bravery, often in battle or an area of special expertise. Since the stem clearly describes a negative quality, the answer must be the only negative term among the options.

Step-by-Step Solution:
Step 1: Identify the polarity of the definition, which is negative because it refers to lack of skill.Step 2: Recall the meanings of each option. Ineptitude means clumsiness or incompetence. Dexterity is manual skill. Proficiency is a high level of skill. Prowess is exceptional ability or bravery.Step 3: Match the negative definition with the negative word, which is ineptitude.Step 4: Confirm that dexterity, proficiency and prowess are antonyms rather than synonyms of the given phrase.Step 5: Select ineptitude as the correct one word substitution.

Verification / Alternative check:
Use the words in example sentences. His ineptitude at driving caused several minor accidents clearly uses ineptitude in the sense of lack of skill. Her dexterity amazed everyone at the workshop, His proficiency in mathematics won him a scholarship and Her prowess on the tennis court impressed the spectators all show high levels of ability, the opposite of what the question describes. This confirms that ineptitude alone matches the original definition.

Why Other Options Are Wrong:
Option b: dexterity means great skill, especially with hands or body movements, and therefore is the opposite of lack of skill.Option c: proficiency refers to advanced competence and is again the opposite of the definition given.Option d: prowess describes outstanding skill or bravery, often in specialised areas such as sports or combat, and is not aligned with incompetence.

Common Pitfalls:
Because three of the options are positive words that often appear together in contexts praising ability, candidates who skim quickly may mistake the question for one that seeks a synonym of skill. It is crucial to notice the phrase lack of in the stem, which completely changes the requirement. Paying close attention to negative markers such as not, without, lack of and absence of will help you avoid such mistakes in vocabulary questions.

Final Answer:
The correct one word substitution for lack of skill, ability, or competence is ineptitude.