Please choose the correct ending to complete the given sentence: Health: [header] How to prevent syphilis [title] Limit your number of sexual partners. [step] If you are sexually active, you can prevent syphilis by limiting your number of sexual partners. Your risk of contracting syphilis goes up with the number of sexual partners you have.

Ending1: This increases your risk for developing syphilis. [substeps] Use caution when sexual partners treat you negatively. Ending2: This increases the risk of the infection spreading among your partners. [substeps] Make sure you limit your number of partners you have before becoming pregnant or had unprotected sex. Ending3: Sexually active people who have only one partner in a monogamous relationship are safest, as long as neither partner has sex with anyone else. For some people, however, this might be unrealistic. Ending4: Decreasing your number of sex partners can prevent the spread of it. [substeps] Avoid having sex with people who are not in your group of partners.

Answer format: ending1/ending2/ending3/ending4