Choose the correct sentence which is built from the words and phrases given:
Vietnam/ children/ free/ medical treatment/ hospitals/ until/ they/ six.
A. In Vietnam, children can get free medical treatment in hospitals until they are six.
B. In Vietnam, children are freed from medical treatment in hospitals until they are six.
C. In Vietnam, children are free of medical treatment in hospitals until they are six.
D. In Vietnam, children are free to choose medical treatment in hospitals until they are six.