She is suspicious ___ people who always want to seem nice and friendly in front of others.a) forb) atc) ofd) with

To determine the correct preposition to fill in the blank, let's analyze the sentence and the options provided.

Sentence Analysis

The sentence reads: "She is suspicious ___ people who always want to seem nice and friendly in front of others." The phrase "suspicious of" is commonly used to express a feeling of doubt or mistrust about someone or something.

Preposition Breakdown

1. a) for - This generally indicates a reason or purpose but does not fit the context of suspicion.
2. b) at - This preposition typically indicates a location or direction and is not used with "suspicious."
3. c) of - This preposition appropriately follows "suspicious," as it denotes mistrust regarding someone or something.
4. d) with - Generally implies a relationship or association and does not fit the context here.

Conclusion

The correct answer is c) of.

Thus, the complete sentence would be: "She is suspicious of people who always want to seem nice and friendly in front of others."