Read the following statements and choose the correct answer option.
In ancient times Indians had imitated the Greek coins, because
a. The weight and size of Indian coins was uncertain.
b. Greek coins were attractive.
c. The weight of Greek coins was certain.
d. Indian coins were punch-marked.
1. a and b are correct but c and d are incorrect
2. a and b are incorrect but c and d are correct
3. All the four causes are incorrect
4. All the four causes are correct