Which of the following statement(s) is/are correct?
1. The child who does not learn tasks at periods of readiness may have great difficulty learning them later.
2. Serious behaviour problems cause abruptly in adolescence, but trace their organ to maladjustment in the early years.
3. In the pattern of development, there is a marked correlation between physical and psychological development.
4. In the pattern of intellectual development, memory precedes reasoning with abstract reasoning following concrete reasoning.