Question

which is the run - on sentence? dolphins swim fast they talk with clicks. dolphins swim fast. they talk with clicks. dolphins swim fast, and they talk with clicks.

Explanation:

A run-on sentence incorrectly joins two independent clauses without proper punctuation or a coordinating conjunction. The first option has two complete thoughts ("Dolphins swim fast" and "they talk with clicks") joined with no punctuation or conjunction, making it a run-on. The second uses a period to separate the clauses correctly, and the third uses a comma plus the coordinating conjunction "and" to properly connect them.

Answer:

Dolphins swim fast they talk with clicks.