SAT Transitions Question

Every US state has an associated state soil, which is typically selected by a group of experts, then passed through the state legislature to receive its official designation. For example, Oklahoma's Port Silt Loam soil was formally designated in 1987, and Maine's Chesuncook soil in 1999. years pass between a soil's selection and official designation, as the legislative process can be notoriously slow. Which choice completes the text with the most logical transition?