Select the most appropriate option with correct usage of the preposition to substitute the underlined segment in the given sentence.

The Centre of Excellence for Data Analytics (CEDA) provides quality data analytic services to various government departments on all levels as well as to public sector units at the Centre and in states.

The correct answer is "various government departments at all levels".

Step-by-step Explanation:

1. Analyze the original sentence:
The underlined segment in the sentence is "various government departments on all levels". The task is to identify if the preposition "on" is used correctly in the context of "all levels" or if it should be replaced by a more appropriate preposition.

2. Evaluate the preposition usage:
- "On all levels" is sometimes used informally, but in standard English, especially when referring to administrative, organizational, or hierarchical structures (like government departments), the preposition "at" is the standard and correct choice.
- We say "at all levels" to denote positions within a hierarchy (e.g., at the local level, at the national level, at all levels of government).
- Therefore, "on all levels" is grammatically inappropriate here and needs substitution.

3. Examine the options:
- "various government departments through all levels": The preposition "through" implies movement from one side to the other or throughout a process, which is incorrect in this context.
- "various government departments from all levels": The preposition "from" denotes a point of origin, which does not fit the intended meaning of providing services to departments situated at those levels.
- "various government departments in all levels": The preposition "in" is not conventionally used with "levels" in this structural sense.
- "various government departments at all levels": The preposition "at" correctly indicates the specific point or level in a scale or hierarchy.

4. Conclusion:
Substituting the underlined segment with "various government departments at all levels" makes the sentence grammatically correct and standard.