The characteristic feature of bifid penis is:

The characteristic feature of a bifid penis is the presence of a single urethral meatus. In cases of bifid penis, there is a division of the penile shaft into two distinct segments, giving it a forked appearance. However, despite this separation, the urethra remains unified, resulting in only one opening for urine to exit the body.

This condition can occasionally occur with other anomalies, but the key defining trait of a bifid penis is that, unlike conditions that would present with multiple meatuses or an entirely absent urethral structure, there is still one single path for urinary flow. Other choices imply a more complex or different anatomical presentation than what is characteristic for this condition.