Alignment of Carbon Nanotubes in Electric Fields: How and Why?

[Cesium]

Conducting carbon nanotubes align their primary axises in the direction of static electric field. Why is this?

I am thinking that it's because since this is their longer axis, the gradient of the generated electric field within the nanotubes will be less than in the perpendicular case. Is this the right way to think about this?

 

[Cesium]

Or, alternatively, is it because the charges at the each end of the nanotube will be closer to the electrode of the opposite charge?