Easy question i guess? Which of the following two-dimensional shapes can be rotated to create a sphere?

A. Triangle
B. Square
C. Circle
D. Ellipse

please give an explanation and not just a letter or answer. Thank you.

The federal reserve controls certain interest rates in the united states. investors often try to speculate as to whether the federal reserve will raise or lower rates and by how much. suppose a company conducts extensive interviews with financial analysts, and as a result, predicts that "thefed" will increase rates by an average of 0.25 percentage points every six months for the forseeable future. which type of equation could be used to model the predicted interest rates over the next several years, assuming no other significant changes? a) a linear equation b) a quadratic equation c) a polynomial equation d) an exponential equation