Correct Answer - 3
System has non-trivial solution
`:. |{:(1,,lambda,,-1),(lambda,,-1,,-1),(1,,1,,-lambda):}|=0`
`rAr 1(lambda +1) -lambda (-lambda^(2) +1) -1 (lambda +1) =0`
`rArr lambda +1 +lambda^(3)-lambda -lambda -1=0`
` rArr lambda^(3) -lambda =0`
`rArr lambda =0, +- 1`