Practice question

Geographic range criteria incorporate two spatial concepts: Extent of Occurrence EOO, minimum convex hull encompassing all known occurrences, measuring spread risk, and Area of Occupancy AOO, occupied habitat within EOO measured on standardized 2×2 km grid cells, measuring habitat specialization. Both metrics fall under Criterion B, which also requires fragmentation, few locations, and continuing decline or extreme fluctuations. B1 thresholds address EOO less than 100 km² CR, B2 addresses AOO less than 10 km² CR, crucial for island endemics. Clarity on this principle prevents confusion between in-situ and ex-situ methods often interchanged in examination options.