A trial is conducted on an educational intervention program for low-income children with asthma. To reduce the threat of contamination, 30 buildings in public housing projects throughout Boston are selected and matched into 15 pairs based on demographics. Each building in each pair is subsequently randomized to intervention or control status. This results in 15 intervention buildings and 15 control buildings. Pre- and post-test measures assess mean asthma severity in the intervention and control buildings. Please identify the study design: A Cross-sectional study B Case-control study C Cluster randomized control trial