Step 1: Read the question.
The Indian Councils Act, 1909 is also known by what name?
Step 2: Recall how reforms were named.
British reforms were often named after the Secretary of State and the Viceroy at the time.
Step 3: Identify the people in 1909.
In 1909 the Viceroy was Lord Minto and the Secretary of State was John Morley. So the Act became known as the Minto-Morley Reforms.
Step 4: Note a key feature.
This Act is remembered for introducing separate electorates for Muslims.
Step 5: Eliminate the others.
The Cabinet Mission Plan was 1946. Montagu-Chelmsford Reforms were the 1919 Act. The Cripps Mission was 1942. None matches 1909.
Step 6: Conclude.
The 1909 Act is the Minto-Morley Reforms.
Answer: Minto Morley Reforms