Kev kuaj lub cev thiab tshuaj lom neeg yog ib qho ntawm cov khoom tseem ceeb ntawm kev kuaj sim, thiab nws cov txiaj ntsig kev sim yog lub hauv paus tseem ceeb rau kev txiav txim siab cov khoom zoo. Muaj peb qhov tseem ceeb ntawm kev ua yuam kev hauv lub cev thiab tshuaj lom neeg lub cev: kev ua yuam kev, kev ua yuam kev random thiab tib neeg yuam kev. Tom qab ntawd, dab tsi yog qhov laj thawj tshwj xeeb ntawm txhua qhov yuam kev?