A 25 year old infertile male underwent semen analysis. Results show: sperm count - 15 million/ ml; pH - 7.5; volume - 2 ml; no agglutination is seen. Morphology shows 60% normal and 60% motile sperms. Most likely diagnosis is:a) Normospermiab) Oligospermiac) Azoospermiad) Aspermia