It's the point that's 2.5 units to the left of the y-axis and 5.5 units above the x-axis. (right there on the picture of the graph that you're hiding from us)
Answer: The Materials of separating salt sand and iron fillings is measurement
Explanation: The explanation to the answer is very easy in basic physics
R = 2700 ohm
I = 2.4 mA = 2.4 × 10^(-3) A
I = Q/t
Q = I × t = 2.4 × 10^(-3) × 15 s = 36 C
F=-ks
F=-(390)(.45)
F=-175.5 N
Work=force x displacement
Work= 175.5(0.45)
Work= 78.98 J
Work = ∆E =78.98 J
Answer=79J (first option)
