To solve this question, the user needs to have knowledge about Hindu mythology and Lord Dattatreya. Lord Dattatreya is considered the incarnation of the three supreme deities in Hinduism, namely, Brahma, Vishnu, and Shiva.
Now, let's go through each option and explain why it is right or wrong:
A. Indra: This option is incorrect. Indra is not considered to be a part of the trinity of Hinduism. He is the king of gods in Hindu mythology and is associated with rain and thunder.
B. Maheshwara: This option is incorrect. Maheshwara is another name for Lord Shiva, who is already a part of the trinity of Hinduism.
C. Ganesha: This option is incorrect. Although Ganesha is considered one of the most important Hindu deities, he is not a part of the trinity of Hinduism.
D. Sai Baba: This option is incorrect. Although Sai Baba is a revered spiritual leader in India, he is not considered a part of the trinity of Hinduism.
Therefore, the correct answer is:
The Answer is: B. Shiva (Maheshwara) is already a part of the trinity of Hinduism. Lord Dattatreya is considered the combined incarnation of Brahma, Vishnu, and Shiva.