Floor of Petit triangle is formed by-

Ans. is 'b' i.e., Internal oblique The lumbar triangle (Petit's triangle) is a weak area in the posterior part of the abdominal wall. It is bounded anteriorly by the posterior margin of the external oblique muscle, posteriorly by the anterior border of the latissimus dorsi muscle, and inferiorly by the iliac crest. The floor of the triangle is formed by the internal oblique and the transversus abdominis muscles.