Concept:
Testosterone is the primary male sex hormone responsible for the development of male reproductive organs and secondary sexual characters.
Examples of secondary sexual characters include:
• Deepening of voice
• Growth of facial hair
• Muscle development
• Broadening of shoulders
Step 1: Understanding where testosterone is produced.
In males, testosterone is produced by specialized cells called Leydig cells present in the:
\[
\boxed{\text{Testes}}
\]
The testes are the main reproductive organs in males and perform two major functions:
• Production of sperm
• Secretion of testosterone hormone
Step 2: Elimination of incorrect options.
• Option (1) Scrotum: Scrotum is only a sac that protects the testes.
• Option (3) Urethra: Urethra is a tube that carries urine and semen outside the body.
• Option (4) Seminal vesicles: These glands produce seminal fluid but not testosterone.
Hence, the correct answer is:
\[
\boxed{(2)\ \text{Testes}}
\]