In interval notation, square brackets indicate that a function can take on that value (or uses a less/greater than or equal to sign). Parenthesis indicate that a function cannot take on that value (or uses a less/greater than sign).
In the case of the given set, both inequality signs are less/greater than or equal to. This indicates to us that we will use brackets in both instances because the set can be equal to -2 and 2.
Answer: [-2,2]
Answer Choice: D
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