Answer :
Based on the fact that Professor Ahmad collected the data from 1-year-olds over 5 years, this is longitudinal research.
what is longitudinal research?
this refers to when researchers try to observe the same phenomenon or group of people over a period of time.
the fact that the age of the research subjects of Professor Ahmad didn't change from 1-year-old means that this is a longitudinal design.
find out more on longitudinal design at https://brainly.com/question/12976553.
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