The sequence by which electrons travel downhill during aerobic respiration. The se sequence has NADH, oxygen chain of transportation of electron, food and NAD.

Respiration (both aerobic and anaerobic) begins with glycolysis in the cytoplasm of a cell;

1 glucose molecule (C₆H₁₂O₆) is converted into 2 molecules of pyruvate in a 10-step process, consuming 2 ATPs and yielding 4 ATPs;

Additionally, 2 NAD+ molecules are reduced to NADH molecules;

In aerobic respiration, each pyruvate molecule then goes through the link reaction, getting converted to acetyl co-A in the mitochondrial matrix, producing 1 CO₂ molecule and 1 reduced NADH molecule;

Acetyl co-A then enter the Krebs or tricarboxylic acid cycle (TCA) where 2 CO₂, 1 ATP, 3 NADH (by reduction of NAD+) and 1 FADH₂ molecules are produced;

The NADH and FADH₂ molecules produced are electron carriers required for the electron transport chain (ETC);

The electron transport chain consists of 4 proteins within the inner mitochondrial membrane which are involved in the production of ATP by oxidative phosphorylation;

The first protein (C1) is responsible for oxidising NADH to NAD+, releasing energy used to generate the proton motive force (PMF) by pumping the protons (H+ ions) into the intermembrane space and the electrons released are transferred to a ubiquinone molecule;

The second protein (C2) is responsible for oxidising FADH₂ to FADH, also releasing energy used to generate the proton motive force (PMF) and, similarly to C1, the electrons released are transferred to ubiquinone;

The third protein complex (C3) transfers the electrons from ubiquinone to cytochrome C;

Finally, cytochrome C transfers these electrons to the fourth complex (C4), where they combine with free protons in the matrix and O₂ to to produce H₂0;

The PMF is then harvested via an ATP synthase protein where H+ flood back into the mitochondrial matrix, and the energy released is used to generate ATP from ADP and Pi;

ATP is now ready for use for bodily processes requiring it.

c. earths continental crust is thicker than its lithosphere.

because, the lithosphere is the outermost layer of the earth/ 100 km thick and is defined by its machanical properties.the lithosphere contains oceanic and continental crust that varies in age and thickness across locations and geologic time. the lithosphere is the coolest layer of the earth in terms of temperature. the term lithosphere should not be confused with the use of "geosphere" which is used to indicate all of earth systems, including the atmosphere, hydrosphere   and biosphere. the surface of the earth can be divided into the continental crust and the oceanic crust.   the continental crust is made mostly of granite while the oceanic crust is made of basalt. the average thickness of the continental crust is 25 miles and the average thickness of the oceanic crust is 5 miles.   three types of rock, igneous, sedimentary, and metamorphic, make up the surface of the earth. that's why 3 option is preferable.

the glands which are associated with each description is given below: