How does a laser-ranging device work?

A global network of observation stations measures the round trip time of flight of ultrashort pulses of light to satellites equipped with retroreflectors.
powerful source of data for studies of the solid Earth and its ocean and atmospheric systems

Ibelieve it is answer b. provides military aid.

The primarily goals of the zapatistas of mexico in 1994 were land reform and redistribution. it is also included in their demands to have a greater political and cultural autonomy for the indigenous people of chiapas and the rest of mexico.