The growth of the merchant class and trade in Europe had a significant impact on international commerce. Governments and religious leaders played a role, but in a different way than the options you mentioned.
Instead of governments refusing to support trade or religious leaders collecting heavy taxes, the growth of the merchant class and trade actually led to the development of systems of credit by banks. These systems made trade easier by providing merchants with financial resources to conduct business across borders.
So, the correct statement is: Banks developed systems of credit to make trade easier. This allowed merchants to expand their reach and engage in international commerce.
Bartering, on the other hand, was gradually replaced by the use of currencies as trade became more complex and widespread.