To understand why the Simon Commission was opposed by India, the user needs to know the historical context of the commission. The Simon Commission was appointed in 1927 to review and report on the working of the Government of India Act of 1919. The commission was made up of seven British members, with no Indian representation.

Now, let's go through each option and explain why it is right or wrong:

A. Death of Lala Rajpat Rai: This event did contribute to the opposition of the Simon Commission, but it was not the main reason. Lala Rajpat Rai was an Indian nationalist leader who was injured during a protest against the Simon Commission and later died of his injuries. His death sparked further protests and calls for the boycott of the commission, but this was not the primary reason for the opposition.

B. Commission doesn't include Indian: This option is correct. The fact that the Simon Commission did not include any Indian members was a major reason for its opposition. The Indian National Congress and other groups saw this as an insult to India's status as a self-governing nation and a lack of faith in Indian ability to participate in the governance of their own country.

C. System of dyarchy: The system of dyarchy was part of the Government of India Act of 1919, which was being reviewed by the Simon Commission. While the system of dyarchy was controversial and opposed by many Indians, it was not the main reason for the opposition to the Simon Commission itself.

D. Gandhi was not part of the Commission: This option is correct but not relevant to the question. Gandhi was not part of the Simon Commission because the Indian National Congress boycotted it, but this was not the main reason for the opposition.

Therefore, the correct answer is:

The Answer is: B. Commission doesn't include Indian.