Topic: Idioms & Phrases,

Best Answer Explained in Below-:

The phrase "a bolt from the blue" is an idiomatic expression that refers to an unexpected event, particularly one that is sudden and shocking. It originates from the imagery of a lightning bolt striking unexpectedly from a clear blue sky, symbolizing something that occurs without warning. In this context, among the given options, "an unexpected calamity" (C) aligns most closely with the connotation of the phrase.

While the other options—such as an unexpected gift (A), person (B), or place (D)—imply surprise, they generally carry a more neutral or positive connotation. In contrast, a calamity denotes a serious and often catastrophic event, which captures the shocking and disruptive essence implied by "a bolt from the blue." The phrase is frequently used to describe events such as sudden losses, disasters, or other distressing occurrences that catch individuals off guard. Thus, option C is not only accurate but also encompasses the negative and startling implications that the idiom conveys.