Choice A rationale:

This statement is incorrect.

Syphilis is not primarily transmitted through sharing needles.

While syphilis can be transmitted through blood-to-blood contact, it is primarily spread through sexual contact or from mother to fetus during pregnancy.

Choice B rationale:

This is the correct answer.

Direct contact with syphilis sores, known as chancres, can indeed transmit the infection.

Syphilis is a sexually transmitted infection, and contact with syphilis sores during sexual activity is a common mode of transmission.

Choice C rationale:

Syphilis is not mainly spread through respiratory droplets in the air.

It is not an airborne infection, and respiratory transmission is not a common mode of transmission for syphilis.

Choice D rationale:

Using barrier methods like condoms can reduce the risk of syphilis transmission but does not completely prevent it.

Condoms are effective in reducing the risk of many STIs, including syphilis, but they are not 100% foolproof.