Why do most people accept Earth's spherical shape as a scientific fact?

A.) It is a convincing persuasion by authoritative scientists.

B.)It is a consensus agreed upon by most people.

C.) Observations, models, and other evidence prove this as a fact.

D.)The flat-Earth model has no testable hypotheses.

Jenny wants to test the electrical conductivity of two substances dissolved in water. she is preparing the containers for the experiment. which factor is most important for her to control? a) volumes of the solutions b) appearance of the solutions c) temperatures of the solutions d) concentrations of the solutions