Which fact best supports the city planner’s opinion? Designated bike lanes have reduced traffic-related accidents by 43 percent in other cities.
A nearby city’s business district has bike lanes and a much higher population of commuters.
The cost of roadwork in the region has reduced the cost of similar projects by more than 12 percent.
Research has proven that bike commuters are healthier and happier than car commuters.

Designated bike lanes have reduced traffic-related accidents by 43 percent in other cities.

Explanation:

From the information given in the question, the city planner believes that the bike lanes will help drivers and cyclists avoid accidents, and also make the downtown area more attractive to bike commuters.

Based on the above, the fact that best supports the city planner’s opinion is that designated bike lanes have reduced traffic-related accidents by 43 percent in other cities.

i agree definitely that

the correct answer is "dissent"

explanation:

because dissent is when one or more judges express disagreement with the majority in court, in specific legal systems.   an   argument in opposition is presented to the court, with a different interpretation, or application.