Answer:
<em>a. Cross-sectional study</em>
Explanation:
A cross-sectional analysis <em>includes at one particular point in time looking at data from a population.</em> Participants are chosen based on specific variables of interest in this type of study.
For developmental psychology, cross-sectional experiments are often used, but this approach is also used in many other fields, including social science and education.
A different form of a gene
In meiosis? Tetrads maby? When two homologus chromosomes do crossing over they're called tetrads so..