Which of the following is a common feature of the illustrated reactions showing the linking of monomers to form macromolecules? A. 2 identical monomers are joined by a covalent bond
B. 2 different monomers are joined by a covalent bond
C. Monomers are joined by a covalent bond, and a water molecule is produced.
D. Monomers are joined by ionic bonds, and a water molecule is produced.

The answer is atmosphere. there are four spheres of the earth: 1. geosphere (from greek word 'geo' = ground), 2. hydrosphere (from greek word 'hydro' = water), 3. biosphere (from greek word 'bio' = life), and 4. atmosphere (from greek word 'atmo' = air). a magnetosphere is a region of space around astronomical objects controlled by the magnetic field of that object. through the process of elimination, since lightning is present in the air, it can be found in the atmosphere.

Very hard to understand