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.
The two animals which use echolocation are bats and dolphins.
Both hunt their prey by articulating high-pitched sounds and listening for the echoes.
<h3>What is echolocation?</h3>
Echolocation is a method used by bats, dolphins and other animals to select the location of objects using reflected sound. This allows the animals to move around in pitch darkness, so they can guide, hunt, identify friends and enemies, and avoid obstacles.
Thus, bats and dolphins are two animals that use echolocation.
To learn more about echolocation click here:
brainly.com/question/3942501