The correct answer is B) he defied the Tenure of Office Act by firing a cabinet member."
What President Johnson did to warrant articles of impeachment being brought against him was "he defied the Tenure of Office Act by firing a cabinet member."
Congress always had a bad relationship with President Jackson The United States Senate started the impeachment trial for the first time to a US President on March 13, 1868. Senate accused him of having violated the Tenure of Office Act. However, the Senate didn't reach the two-thirds vote majority and Jackson was judged not guilty.