I think it's A. Pressure and heat built up in the magma chamber.
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Weight = electric force
<span>mg = qE </span>
<span>6.64x10^-27 x 9.81 = (2 x 1.60x10^-19) E
</span>qE =mg,
<span>E = mg/q = 6.64•10^-27•9.8/2•1.6•10^-19 =2.03•10^-7 V/m</span>
Her total distance was 200 meters, since she ran 100 meters west and the same 100 meters back. This gives an average speed of 200 m / 40 s = 5 m/s.
However, her displacement was 0, since she ended at the same place she began, therefore, her average velocity is 0 / 40 s = 0.