Step 1: Understanding ejaculatory ducts.
Ejaculatory ducts are formed by the union of vas deferens and seminal vesicle ducts. Step 2: Pathway in male reproductive system.
These ducts pass through the prostate gland and open into the prostatic urethra. Step 3: Elimination of other options.
Spongial and penile urethra are distal parts and do not receive ejaculatory ducts directly. Step 4: Conclusion.
Hence, ejaculatory ducts open into the prostatic urethra.