Concept: The  question tests on a word problem

Solution:

From the question stem, we know that there are a total of 40 pigs or cows. Of these 40, we need to ascertain the number of cows.
Let the number of cows be represented by c and the number of pigs be represented by p. So, we know, p + c = 40

From statement I alone, the farm has more than twice as many cows as pigs. Therefore,
c > 2p.

Plugging values is the best way from here on.
If p = 10, c = 30. However, if p = 12, c = 28. Both these cases satisfy the constraint given in statement I alone and the question data.

We do not have a unique answer from the information given in statement I alone. Statement I alone is insufficient.
Answer options A and D can be eliminated. Possible answer options at this stage are B, C or E.

From statement II alone, the farm has more than 12 pigs. This means that the number of pigs can be any value from 13 to 40 and consequently the number of cows can be any value from 27 to 0.

Statement II alone is insufficient to give us a unique answer. Answer option B can be eliminated. Possible answer options at this stage are C or E.

Combining the information given in statements I and II, we have the following:
c > 2p and p > 12. The smallest value of p is 13 and for this value, c = 27 which is definitely more than twice of 13.

Can we take p as 14? We cannot because more than twice of 14 will give us a value of more than 28 and then the total of 40 will be breached.

Note that we cannot take fractional values here for p or c since they represent countable objects.

Combining statements I and II, we got a unique value for the number of cows. The combination of statements is sufficient to answer the question. Answer option E can be eliminated.

The correct answer option is C