If sinθ and cosθ are roots of the equation x² −bx+c=0, then a,b, and c satisfy which of the following relations?
a) a=1, b² −4ac=0, c=−1
b) a=1, b² −4ac=1, c=1
c) a=1, b² −4ac=0, c=1
d) a=1, b² −4ac=1, c=−1