Question

Roemer's experiment failed because of his ignorance about the what

Answer 1

There are no choices available, however through my research this could be the choices for your question: 

a) the speed of light
b) the dimensions of the earth´s orbit
c) the number of Saturn´s moons
d) the use of the telescope

The most probable answer would be his miscalculations about the dimensions of the Earth's orbit which is why his experiment ultimately failed.

Answer 2

Answer:

dimensions of the Earth's orbit

Explanation: