Mosquitos carry numerous tropical diseases. A public health agency wants to identify the extent of mosquito breeding areas (like standing water) within its community. Comment on the following approaches to determining the extent of breeding areas. (a) Send letters to residents asking them to report the presence of standing water on their property. (b) Ask a sample of doctors in the community to report patients with mosquito-related illnesses. (c) Send inspectors to check for breeding areas in a random sample of geographic blocks (defined by tax records).