The system of inequalities
a−b2≥41b−c2≥41c−d2≥41d−a2≥41where a,b,c,d are real numbers has
<spanclass=′latex−bold′>(A)</span>no solutions<spanclass=′latex−bold′>(B)</span>exactly one solution<spanclass=′latex−bold′>(C)</span>exactly two solutions<spanclass=′latex−bold′>(D)</span>infinitely many solutions