The open-loop transfer function with unity feedback are given below for different systems 1. G(s) = 2 s + 2 2. G(s) = 2 s(s + 2)3. G(s) = 2 s2(s + 2) 4. G(s) = 2(s + 1) s(s + 2) Among these systems, the unstable system is

• 1. G(s) = 2
• 2. G(s) = 2
• 3. G(s) = 2
• 4. G(s) = 2(s + 1)
• A. 1
• B. 2
• C. 3
• D. 4