Why does electronegativity decrease from right to left within a period? the sizes of the atoms increase. the sizes of the atoms decrease. the total positive charge in the nucleus increases. the total positive charge in the nucleus decreases?

Since atomic number increases down a group and electronegativity increases from left to right. We can say that due to the fact that there is an increase in distance between valence electrons and the nucleus, in other words, the radius of the atoms increases down a group. Based on this information we can conclude that the answer is a. 

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