The correct answer is option no. ($4$) as

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($A$) is $FSH$ which is a pituitary hormone.

($B$) is Leydig cells which are found in the interstitial space outside of the seminiferous tubules.

($C$) is Sertoli cells are found inside the seminiferous tubules.

($D$) is Spermiogenesis which is a process that helps in transformation of spermatids into spermatozoa.