Final answer:
Carbon, which is located to the right of Boron and Lithium in the periodic table, has the greatest electron affinity among the three because of increased nuclear attraction for additional electrons due to its smaller atomic radius and higher atomic number.
Step-by-step explanation:
The element among Carbon, Boron, or Lithium that would have the greatest electron affinity is Carbon. Electron affinity is the energy change when an electron is added to a neutral atom to form a negative ion. When moving across a period in the periodic table from left to right, electron affinity generally increases because the atoms are smaller and the added electron is closer to the attracting nucleus. Carbon, being to the right of Boron and Lithium in the second period, would thus typically have a higher electron affinity than Boron, and significantly more than Lithium, which is the first element of the period with very low electron affinity due to its larger size and lesser nuclear attraction on additional electrons.