A statement takes a period. A direct question takes a question mark. An exclamation point is almost never the ACT answer. The test is not grading excitement. Punctuation overall is in ACT punctuation rules.
Direct versus reported
Where is the test center? needs a question mark. She asked where the test center was. is a statement and takes a period. If the question is inside quotes, the mark usually sits inside the quotes, in quotation marks.
A period and a semicolon both end a complete sentence when joining two clauses. That overlap is in period and semicolon as the same job. STOP versus GO is in STOP versus GO punctuation.
The bottom line
Question mark only for a question you could ask out loud. Otherwise a period. Skip the exclamation point.
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This article offers general ACT prep guidance. The ACT can change from year to year, including its format, scoring, policies, test dates, and fees, so always confirm the latest details on the official ACT website at act.org before you make decisions. ACT® is a registered trademark of ACT, Inc. thirty-six is not affiliated with, endorsed by, or sponsored by ACT.