Which type of needles is most likely to cause needlestick injuries?

The option indicating regular needles is considered most likely to cause needlestick injuries due to their design and handling practices. Regular needles, which lack any built-in safety features, require users to manually handle and recap them after use. This process increases the risk of inadvertent pricks during the re-capping or disposal stages.

In contrast, safety-engineered needles are specifically designed to reduce the likelihood of needlestick injuries by incorporating mechanisms that shield the needle after use. Unused needles pose no risk of injury, and re-capped needles exacerbate the risk due to improper handling. Therefore, the reliance on regular needles, coupled with the manual actions involved post-use, significantly enhances the chances of accidental injury, making them the most hazardous option in terms of needlestick injuries.