Concept:
Humans belong to the order Primates and share evolutionary ancestry with other primates.
• Closest relatives of humans are great apes (chimpanzee, gorilla, orangutan).
• Among given options, orangutan is the closest relative.
Step 1: Understand evolutionary relationship.
Humans evolved from a common ancestor shared with great apes.
Step 2: Analyze options.
• (A) Lemurs: Primitive primates
• (B) Tarsiers: Intermediate primates
• (C) Baboons: Monkeys
• (D) Orangutan: Great ape (closest among options)
Step 3: Conclusion.
Thus, humans are most closely related to orangutans among given options.
Final Answer: Option (D)