The surface temperature of the Sun is nearly :

The surface of the Sun, known as the photosphere, is the visible layer from which most solar radiation is emitted [c1][t2]. Scientific measurements, including spectroscopy and analysis of SOHO mission data, indicate that the effective temperature of the photosphere is approximately 5772 K to 5778 K [t3][t5][t8]. In many standard educational texts and general scientific contexts, this value is rounded to 6000 K for simplicity [t2][t4]. While the Sun's core reaches extreme temperatures of about 15 million K due to nuclear fusion, the temperature decreases significantly toward the outer layers [t2][t6]. Although some sources cite the temperature as 6000C (which would be approximately 6273 K), the most widely accepted scientific approximation for the Sun's surface temperature in Kelvin is 6000 K [c1][c2][t2]. Therefore, option 3 is the most accurate choice.

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 2: The Solar System > Photosphere > p. 23
2. [2] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 2: The Earth's Crust > The Solar System > p. 2