Having multiple sexual partners poses a greater risk because not everybody is infected but the chances of somebody having a sexual relationship with an infected person, given he/she has many sexual partners, are higher.
Answer:
![\boxed{\bf~Having~multiple~sexual~partners - Last~option.}](https://img.qammunity.org/2019/formulas/health/middle-school/wlftkrr5sk01fq08kirsteh3jhahzejho9.png)
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