$A$ part of the male reproductive system is shown below. Study the diagram and answer the questions that follow.
$(a)$ Two parts have been incorrectly labelled. Identify them.
$(b)$ Give the function of urethra.
$(c)$ Which hormone is released by testis?

(N/A) In the provided diagram,the labels for 'Testis' and 'Penis' are swapped. The structure labeled as 'Testis' is actually the 'Penis',and the structure labeled as 'Penis' is actually the 'Testis' (within the scrotum).
$(b)$ The urethra serves as a common passage for both sperms and urine in the male reproductive system.
$(c)$ The testis releases the hormone 'Testosterone',which is responsible for the development of secondary sexual characteristics in males.