Task: Question Answering
Input (English): Passage: By this time, Etty had developed a great admiration for the portrait painter Thomas Lawrence, and hoped to learn from him. Having arranged an introduction via Henry Fuseli, Etty's uncle William met with Lawrence and paid him 100 guineas (about £8,200 in 2019 terms) in return for his accepting the younger William as a private pupil for a year.Under this arrangement Etty did not receive formal tuition from Lawrence. Instead, Lawrence set aside a room in his attic for Etty to copy from his pictures, and agreed to answer questions when he was in a position to do so. Etty found the experience of copying Lawrence's work extremely frustrating, and in his own words "was ready to run away", but he persisted and eventually taught himself to copy Lawrence's work very closely. Although Etty found his year with Lawrence a frustrating experience, his development of the ability to copy other works served him in good stead in future when he came to copy elements from the Old Masters.Once he had completed his year with Lawrence, Etty returned to the Royal Academy, drawing at the life class and copying other paintings, as well as undertaking commissions and doing occasional work for Lawrence to earn money. He was unsuccessful in all the Academy's competitions, and every painting he submitted for the Summer Exhibition was rejected.In 1809 Etty's uncle William, with whom he had been staying, died. He was forced into an inconvenient transient lifestyle, moving from lodging to lodging. Etty had been left a significant sum in his uncle's will, and his brother Walter now took over their uncle's position at Bodley, Etty and Bodley, giving Walter the means to support the younger William's work financially. In 1811 Etty's persistence paid off. Two of his paintings were accepted for the Telemachus Rescues Antiope from the Fury of the Wild Boar exhibition at the Royal Academy Summer Exhibition, and Sappho at the British Institution. The latter sold for the respectable sum of 25 guineas (about £1,800 in 2019 terms). Although from now on Etty had at least one work accepted for the Summer Exhibition each year, he had little commercial success and generated little interest over the next few years. By 1814, Etty was becoming widely respected at the RA for his use of colour and in particular his ability to produce realistic flesh tones. 
Question: Whose painting Sappho was accepted for exhibition at the British Institution?
Output (English): Etty.