The correct sentence from the options you provided is:
"The bike on the bike rack is blue."
The other sentences contain subject-verb agreement errors:
- "The surface of the parking lots was redone this summer." (singular subject "surface")
- "The sidewalks in the courtyards have been decorated with chalk." (plural subject "sidewalks")
- "The cars in the parking lot belong to the teachers." (plural subject "cars")