Secondary sources is the right one
Hitler violated the Treaty of Versailles in a number of ways.
Firstly, he began rearmament in 1935. Under the Treaty of Versailles Germany's military was limited to 100,000 men, but between 1933 and 1939 the German army increased from 100,000 men to 500,000. He also said that Germany was going to build up an airforce of over 2500 aircraft and expand their navy, thus the creation of the Luftwaffe broke the terms laid out by the Treaty of Versailles.
Expanding the navy was achieved by convincing Britain to sign the Anglo-German Naval Agreement which allowed Germany to build up its fleet to 35% of the size of the Royal Navy which had been forbidden under the terms of the <span>Treaty of Versailles.</span>
As part of his plan for rearmament he introduced conscription, increasing the size of the army. Although this is part of the same point, some exam boards allow points for both answers.
Those are the main things that we got at GCSE really so I hope they help somewhat