Step 1: Understanding the Question:
The question asks for the appropriate preposition to complete the sentence where the adjective ``responsible'' is used.
The sentence discusses a duty or task assigned to an individual.
Step 2: Key Concepts and Grammar Rules:
The adjective ``responsible'' can take different prepositions depending on the noun that follows it.
We use ``responsible for'' when referring to a duty, action, or person in one's care.
We use ``responsible to'' when referring to an authority figure, superior, or governing body.
Step 3: Detailed Explanation:
• Option (B) - for: In the given sentence, the object following the blank is ``the economic development'', which is a duty or task.
Therefore, the correct preposition is ``for'', meaning she has the obligation to ensure the economic development of the company.
• Option (A) - to: This would be used if the sentence referred to an authority, such as ``She is responsible to the Director''.
Since ``economic development'' is not an authority figure, ``to'' is incorrect here.
• Options (C) and (D) - with / of: These do not collocate with ``responsible'' in this standard grammatical construction.
Step 4: Final Answer:
The grammatically correct choice is ``for'', which corresponds to Option (B).