The best and most correct answer among the choices provided by your question is the second choice or letter B.
<span>Regarding the second electron affinity for an oxygen, i. e., the electron affinity for O-, it is much larger and negative.</span>
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<span>The equation you used is KE=hv-hv0, where h=6.63*10^-34 (constant). You multiply h by 1.5*10^15. Multiply h by the threshold freq of cesium (from part A). Subtract the second answer from the first answer, and you get the kinetic energy. Hope this helps.</span>