The correct answer is: c) Ektara.
The Ektara is a traditional stringed instrument from India and Bangladesh. It is a simple instrument, consisting of a single string stretched over a gourd resonator. The string is played with a bow, and the instrument is used to accompany singing and dancing.
The Pena is a traditional stringed instrument from Manipur, India. It is a long-necked lute with four strings. The Pena is played with a plectrum, and is used to accompany singing and dancing.
The Sarinda is a traditional stringed instrument from Rajasthan, India. It is a long-necked lute with three strings. The Sarinda is played with a bow, and is used to accompany singing and dancing.
The Dotara is a traditional stringed instrument from Bangladesh. It is a long-necked lute with two strings. The Dotara is played with a plectrum, and is used to accompany singing and dancing.