Match each graph to its equation. Instructions: enter the letter only (A, B, etc.)
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A $y= \left\{\begin{array}{ll} 1 & x<0 \\ x & x \ge 0 \end{array}\right.$
B $y= \sqrt{x}$
C $y= | x |$
D $y= 1 - x$
E $y= x^3$
F $y= x^2$