If 2 is multiplied to each even digit and 2 is added to each odd digit in the number 2434251 , what will be the sum of the digits which will appear more than once in the new number thus formed?

Given: 2 is multiplied to each even digit and 2 is added to each odd digit in the number 2434251,

Now, 2434251 $$\rightarrow$$ 4858473

4 and 8 is appear more then once. 

4 + 8 = 12

Thus, the correct answer is (a).