How many repeating units make up a sea urchins test

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answer: collecting information/data

reason: the student is going around and asking people questions to collect data

i hope this

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.