Answer and Explanation:
The best way to revise the sentence "While we were waiting for the bus and it started to rain" is option B: "While we were waiting for the bus, it started to rain."
Option B provides a clear and concise revision that maintains the logical connection between waiting for the bus and the occurrence of rain. It uses a comma to separate the dependent clause "While we were waiting for the bus" from the independent clause "it started to rain." This punctuation choice helps to clarify the relationship between the two actions and improves the overall readability of the sentence.
Options A, C, and D introduce incorrect punctuation or remove necessary conjunctions, which can lead to confusion or ambiguity in the sentence.
In option A, the use of a comma before "and rain started" creates a sentence fragment. It lacks a main verb, making it incomplete and grammatically incorrect.
Option C replaces the comma with a semicolon, which is not suitable in this context. Semicolons are typically used to join two independent clauses that are closely related. However, in this sentence, "it started to rain" is not an independent clause on its own and cannot stand alone as a complete sentence.
Option D removes the necessary comma before "it started to rain." Without the comma, the sentence becomes a run-on sentence, combining two independent clauses without proper punctuation or conjunctions.
Therefore, option B is the most appropriate revision, providing clarity and maintaining proper grammar and punctuation.