With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: The Challenge was renamed Real Earth/Road Rules Challenge.
text_B: Sun Link , also known as the Tucson Streetcar , is a single-line streetcar system in Tucson , Arizona , United States , that began service in July 2014 .. Streetcar. Streetcar. Tucson. Tucson, Arizona. Arizona. Arizona. United States. United States. streetcar. streetcar. The system 's 3.9 mi route connects the Arizona Health Sciences Center -LRB- including University Medical Center -RRB- , the University of Arizona campus , the Main Gate and 4th Avenue shopping and entertainment districts , downtown Tucson , the Tucson Convention Center , and the Mercado District under development west of Interstate 10 .. Tucson. Tucson, Arizona. Arizona. Arizona. Arizona Health Sciences Center. University Medical Center ( Tucson, Arizona ). University Medical Center. University Medical Center ( Tucson, Arizona ). University of Arizona. University of Arizona. Tucson Convention Center. Tucson Convention Center. Interstate 10. Interstate 10 in Arizona. The streetcar project 's overall cost of $ 196 million was met through a combination of local funding sources and federal grants .. streetcar. streetcar. The streetcar shares a common payment system with the Sun Tran regional bus service .. streetcar. streetcar. Sun Tran. Sun Tran
not_related.