S3 : x4 + x2 + 1 = 0
\(x^2=\frac{-1\pm\sqrt{1-4}}{2}-\frac{-1\pm\sqrt{3i}}{2}\)
∵ x2 is not real
∴ x is not real
Hence, number of real roots of x4 + x2 + 1 = 0 is zero.
∵ S3 is true and option (D) is only option which contains s3.
∴ Option (D) is true.
