Topic: Group verb,

Best Answer Explained in Below-:

The correct answer is B) "in, by" because it accurately conveys the circumstances of how John and his friend died in a grammatically correct and idiomatic manner.

In English, the preposition "in" is commonly used with "sleep" to indicate that someone died while they were asleep. The phrase "died in sleep" suggests that John's passing occurred during his sleeping hours, implying a peaceful context, which is a widely understood expression.

On the other hand, "by" is the appropriate preposition to use with "accident". When we say someone died "by accident," it indicates that their death resulted from an unforeseen or unintentional event. This phrase effectively communicates the nature of the friend's demise, emphasizing that it was not deliberate or planned.

The other options, such as "at" or "of" for John's death, do not convey the meaning accurately or idiomatically. Similarly, using "in" with "accident" or "over at" is also grammatically incorrect in this context. Therefore, "in sleep" and "by accident" are the precise, idiomatic choices that best fit the intended meanings of the sentences.