The correct answer is: "abstinence".
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Note: "Abstinence" is, in fact, the only "100%" effective form of birth control".
If one "abstaining" (i.e., resisting, not participating in, refraining) from "having sex" [particularly, penile-vaginal sex; as well as various other risky activity, then one "cannot get pregnant" or "cannot get someone pregnant."
{Note: since if one does not "have sex", one [a female] cannot
"get pregnant"; and one [a male] cannot "get someone pregnant" .
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Note that this answer is not a "silly" or "non-sense answer".
Note that "abstinence" is not only considered "100% effective" — but also considered specifically a "[100% effective] form of birth control " — in MANY health education/sex education classes, manuals, instructor manuals, agencies such as Planned Parenthood.
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