Answer:
B.
Step-by-step explanation:
The sentence that demonstrates incorrect subject-verb agreement is:
B. We all starts from the same point, but I knew going into the race that it was going to be harder than I originally thought.
In this sentence, the subject ("We") is plural, but the verb ("starts") is in the singular form. In order to correct the subject-verb agreement, the verb should be changed to the plural form: "We all start from the same point..."