What is credibilty cause i dont now

All of the following were weaknesses of the articles of confederation, except: a) the central government was not permitted to regulate state, interstate, or foreign trade. b) the central government was not permitted to borrow money. c) the central government had little ability to regulate money. d) the central government had no ability to tax.

Who did the first work in creating vaccines

Which of the following best describes the aztecsa) skilled engineersb) peaceful farmers c) skilled writers d) mountain dwellers