Parts of the following sentence have been given as options. Select the option that contains an error.
"We were driving home when suddenly a deer runs across the road."

The sentence establishes a past context with the past continuous action "We were driving". An action that suddenly interrupts an ongoing past action must be in the simple past tense. Therefore, the present tense verb "runs" should be replaced with the past tense verb "ran".
* Incorrect: ...a deer runs across the road
* Correct: ...a deer ran across the road