Explanation:
The October Manifesto was a document issued by Tsar Nicholas II of Russia in response to the 1905 Russian Revolution. It was an attempt to appease the revolutionary movements and address the demands of the people. The October Manifesto introduced several significant reforms that aimed to improve the political and social conditions in Russia.

The features of the October Manifesto were:

1. Freedom of speech, press, and association:
The October Manifesto guaranteed freedom of speech, press, and association. This meant that people could express their opinions freely, newspapers could publish without censorship, and individuals were allowed to form political and social organizations.

2. Power to make laws conferred on the Duma:
The Manifesto granted the power to make laws to the newly established legislative body called the Duma. The Duma was an elected parliament with representatives from different social groups, including peasants, workers, and nobility. This was a significant shift in power, as it allowed for a more representative political system.

3. Authority of the Tsar was reduced:
One of the key aspects of the October Manifesto was the reduction of the Tsar's authority. The Manifesto acknowledged the need for reform and recognized the importance of sharing power with the people. This was a significant departure from the autocratic rule of the Tsar and marked the beginning of a more constitutional monarchy.

4. Final decision-making power was vested in the Tsar:
Contrary to the other options given, the October Manifesto did not vest the final decision-making power solely in the Tsar. While the Tsar still held significant authority, the introduction of the Duma and the recognition of the rights and freedoms of the people signaled a shift towards a more democratic system. The Duma had the power to propose and pass laws, and the Tsar was required to approve them. This meant that the Tsar's decisions were not absolute and could be influenced by the elected representatives.

In conclusion, the correct answer is option 'D': Final decision-making power was vested in the Tsar. The October Manifesto aimed to introduce reforms that would share power with the people and establish a more representative political system through the creation of the Duma.