Answer:
(D) planet Uranus
Step-by-step explanation:
William Herschel was a British astronomer. He made a large telescope for sky surveys. In the year 1781, on the day of 13th March he discovered a new object in the constellation of Gemini. On further investigation this was proved to be a new planet of the Solar system and later named as Uranus.
This was a very important discovery as this was the first planet discovered after Saturn also which can not be seen through naked eyes. Along with Uranus he also discovered Infrared radiation and few moons of Saturn and Uranus.