The correct option is option 2: "It made the Central Executive responsible to the Legislature." This statement is not correct.

Explanation of each option:

1) Option 1: It extended the practice of communal representation: This is a correct statement. The Government of India Act 1919 did introduce the concept of communal representation by providing separate electorates for Muslims, Sikhs, and Europeans.

2) Option 2: It made the Central Executive responsible to the Legislature: This statement is not correct. The Government of India Act 1919 did not make the Central Executive responsible to the Legislature. Instead, it expanded the role and powers of the legislature by introducing the concept of dual government and provincial autonomy.

3) Option 3: It is also known as the Montague-Chelmsford Reforms: This is a correct statement. The Government of India Act 1919 is commonly referred to as the Montague-Chelmsford Reforms because it was introduced by Edwin Montague, the Secretary of State for India, and Lord Chelmsford, the Viceroy of India at the time.

4) Option 4: It paved the way for federalism by clearly separating the responsibilities of the Centre and the Provinces: This is a correct statement