There are twofactors which determine an individual's intelligence. The first is the sort ofbrain he is born with. Human brains differ considerably, some being morecapable than others. But no matter how good a brain he has to begin with, anindividual will have a low order of intelligence unless he has opportunities tolearn. So the second factor is what happens to the individual—the sort ofenvironment in which he is reared. If an individual is handicappedenvionmentally ,it is likely that his brain will fail to develop and he willnever attain the level of intelligence of which he is capable. Theimportance of environment in determining an individual's intellingence can bedemonstrated by the case history of the identical twins, Peter and Mark X.Being identical, the twins had identical brains at birth, and their growthprocesses were the same. When the twins were three months old , their parentsdied, and they were placed in separate foster homes. Peter was reated byparents of low intelligence in an isolatedcommunity with poor educationalpooprtunities.Mark was reared inthe home of well-to-do parents who had been tocollege. He was read to as a child , sent to good schools, and given everyopportunity to be stimulated intellectually.This enviromental differencecontinued until the twins were in their late teens, when they were giben tesetsto measure their intelligence. Mark's I.Q. was 125, twenty-five points higherthan the average and fully forty points higher than his identical brother.Given equal opportunities , the twins , having identical brains,would havetested at roughly the same level. 1.Thisselection can best be titled_________. a.MeasuringYour Intelligence b.Intelligenceand Environment c.TheCase of Peter and Mark d.Howthe brain Influences Intelligence 2.Thebeststatement of the main idea of this passage is that _____. a.humanbrains differ considerably b.thebrain a person is born with is improtant in determining his intelligence c.environmentis crucial in determining a person's intelligence d.persons having identical brains will have roughly the same intelligence 3.Accordingto the passage , the average I.Q.is _____. a.85 b.100 c.110 d.125 4.Thecase history of the twins appears to support the conclusion that _______. a.individualwith identical brains seldom test at same level b.anindividual's intelligence is determined only by his enviroment c.lackof opportunity blocks the growth of intelligence d.changesof enviroment produce changes in the structure of the brain 5.Thispassage suggests that an individual 's I.Q.______. a.canbe predicted at birth b.staysthe same throuthout his life c.canbe increased by education d.isdetermined by his childhood