Physics terminal velocity question

[Skarl]

"Which has a greater terminal velocity when falling through the air, a 1000-kg boulder (with a cross-sectional area of 5 m^2) or a 1.0-gm pebble (with a cross-sectional area of 5 cm^2)?"

The answer is that there is insufficient information because we don't know C, which depends on the objects' shape. Specifically, here is the equation given in the passage for terminal velocity:

My main confusion lies in how cross-sectional area relates to shape. Are the two not correlated/related? So knowing cross-sectional area, don't we also know C to an extent (enough to determine a qualitative relationship or greater/less)?

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[Doogie.Howser]

A cross-sectional area can't tell you the shape of the object. A cube can have a cross-sectional area of 5 m^2, and a sphere can also have a cross-sectional area of 5 m^2. C is the drag coefficient that doesn't solely rely on an objects' shape, but also the density, size, and other factors.

That sounds like a frustrating question because one could assume that the density of the two objects are the same and the only difference is the area. But you can't say for certain that one has a greater/lesser drag coefficient.