The correct answer is: A. Nimbarka
Nimbark, also known as Nimbarkacharya, was a 12th-century Indian philosopher and theologian who founded the Nimbarka Sampradaya, one of the four major Vaishnava sampradayas. He is best known for his work the Bhedabheda Tattva Viveka, which expounds his philosophy of bhedabheda, or qualified non-duality.
The Dasa Sloki is a short poem that is part of the Bhedabheda Tattva Viveka. It deals with the three realities (tri-tattava) –Brahma (Krishna), soul (Chit) and matter (Achit). The poem states that Brahma is the supreme reality, and that the soul and matter are both dependent on him. However, the soul and matter are also real in their own way, and they are not completely absorbed into Brahma.
The other options are incorrect because they are not the authors of the Dasa Sloki. Ramanuja was a 12th-century Indian philosopher and theologian who founded the Sri Vaishnava Sampradaya. Madhva was a 13th-century Indian philosopher and theologian who founded the Dvaita Vedanta school of thought. Vallabhacharya was a 16th-century Indian philosopher and theologian who founded the Pushtimarga sect of Vaishnavism.