The thiazole derivative A is acidic due to the "resonance effects of the thiazole ring." Draw a good resonance structure or structures of the resulting carbanion B, and briefly explain in words why your resonance structure supports the observation that A is acidic. (Recall, a strong acid has a stable conjugate base.) Briefly explain.

15. which of the following is not human-caused groundwater pollution? a. water in an aquifer dissolves elements such as arsenic and mercury from surrounding rock. b. water in an aquifer is contaminated by leachate that seeps into the ground from a landfill. c. water in an aquifer becomes polluted with chemicals used in hydraulic fracturing, or fracking. d. water in an aquifer absorbs harmful bacteria from the drainage field of a septic tank.