Correct Answer:
B. so
The correct answer is B: so. The structure "so...that" is a common grammatical construction used to express a cause-and-effect relationship or a degree of something that leads to a particular result. In the sentence, "She is so intelligent that she solved the puzzle instantly," her high level of intelligence (the cause) directly led to her ability to solve the puzzle quickly (the effect). This construction emphasizes the extent of her intelligence.
- A: very is an intensifier, but it doesn't typically precede "that" to form a cause-and-effect clause.
- C: much is generally used with comparatives or to quantify uncountable nouns, not in this specific degree-and-result structure.
- D: too implies an excessive degree, often with a negative connotation, and is usually followed by "to" (e.g., "too intelligent to be fooled"), not "that".
Therefore, "so" is the only option that correctly completes the sentence's intended meaning and grammatical structure.