Option A: 70 + p
Since you start with a weight of 70 and "p" is added to that 70 pounds a year later, the expression "70 + p" is the dog's weight after a year.
Dividing, subtracting, and multiplying do not make sense in this problem as "p" is only representative of a definite amount of pounds added to that original amount of 70 one year later.
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