From experimental data, a plot of absorbance (in arbitrary units, a.u.) at a wavelength of 630 nm (on the y-axis) was plotted against the concentration (in mg/L) of Cu2+ (on the x-axis) in known solutions and a linear relationship was found with an equation of y = 9.52x+0.07. If an unknown solution had an absorbance of 0.84 a.u. at a wavelength of 630 nm, what is its concentration of Cu2+? O a. 0.081 mg/L 0 b, 0.096 mg/L O c. 8.7 mg/L O d. 7.3 mg/L