Final answer:
The transmission-based precaution that should be taken when conducting a streptococcal pharyngitis test is droplet precaution.
Step-by-step explanation:
When conducting a streptococcal pharyngitis test, the transmission-based precaution that should be taken is droplet precaution. Streptococcal pharyngitis is primarily transmitted through coughing and sneezing, which can release infectious droplets into the air. By implementing droplet precaution measures such as wearing a mask, the spread of the infection can be limited.