Many cities have introduced bike-sharing programs to reduce traffic congestion and promote eco-friendly transportation. Studies show that in cities with proper infrastructure, such as bike lanes and safe parking, these programs reduce car usage and lower carbon emissions. However, in cities lacking such infrastructure, bike-sharing programs often struggle to succeed, resulting in minimal impact on traffic and pollution.

Which of the following most accurately describes the cause-and-effect relationship in the passage?

Option D accurately reflects the passage's main argument: the success of bike-sharing programs depends on supporting infrastructure like bike lanes and safe parking. This infrastructure enables these programs to effectively reduce traffic congestion and pollution, creating a clear cause-and-effect relationship. Without adequate infrastructure, the programs struggle to achieve their goals, as stated in the passage.

Option A: Incorrect. The passage does not claim that bike-sharing programs reduce traffic in all cities. It specifies that success depends on infrastructure.

Option B: Incorrect. While infrastructure is necessary, the passage does not claim it guarantees success in all cities.

Option C: Incorrect. The passage focuses on the effects of bike-sharing programs, not general preferences for alternative transportation.

Option E: Incorrect. The passage clearly states that reduced carbon emissions depend on the success of bike-sharing programs, not their mere presence.

Hence, the correct answer is Option D