Correct Answer - Option 2 : Unstable
Concept:
For plane truss:
If, (m + 3) = 2j ⇒ Perfect, stable truss
If, (m + 3) < 2j ⇒ Deficient or Unstable truss
If, (m + 3) > 2j ⇒ Redundant or Indeterminate truss
Where,
m = Total number of member
j = Total number of joint