Final answer:
The correct answer is A. 'electronegativity; increases'. Electronegativity is the relative ability of an atom to attract shared electrons in a bond and it increases as the atom's size decreases.
Step-by-step explanation:
The relative ability of a bonded atom to attract shared electron pairs is called its electronegativity. This ability increases as the size of the atom decreases because for a smaller atom the shared electrons will be closer to the nucleus. Therefore, the correct answer is A. electronegativity; increases.
Electronegativity is a measure of the tendency of an atom to attract shared electrons when it forms a covalent bond. As atoms get smaller, their ability to attract electrons in a bond increases. This is distinct from electron affinity, which is the energy change when an isolated atom gains an electron, and is not a measure of attraction in a bonded situation.
It is important to note that electronegativity is not a measurable physical quantity like electron affinity, but rather a calculated, dimensionless value that helps predict bonding behavior.