The answer is d because it said so
<span>the lithosphere, which contains all of the cold, hard, solid rock of the planet's crust (surface), the hot semi-solid rock that lies underneath the crust, the hot liquid rock near the center of the planet, and the solid iron core (center) of the planet </span>the hydrosphere, which contains all of the planet's solid, liquid, and gaseous water,and the atmosphere, which contains all of the planet's air
When a molecule is going through any physical change, solid to liquid or liquid to gas, as it changes, the temperature remains constant. it does not increase or decrease, it stays at that temperature/.
For example, water evaporates/ boils at 100 C. if you are heating water to the point of boiling, it will remain 100 C until all the water evaporates. Once it becomes a gas, the temperature will continue to increase
I believe the answer is C.
Explanation:
(a) 
This is acid base reaction because there is no change of oxidation state on either side of the reaction.
(b) 
This is a oxidation reduction reaction because sodium in elemental state ( 0 oxidation state) oxidizes to Na⁺ in NaCl. Also H⁺ in HCl reduces to H° in H₂.
(c) 
This is a oxidation reduction reaction because magnesium in elemental state ( 0 oxidation state) oxidizes to Mg²⁺ in MgCl₂. Also Cl° in Cl₂ reduces to Cl⁻ in MgCl₂.
(d) 
This is acid base reaction because there is no change of oxidation state on either side of the reaction.
(e) 
This is a oxidation reduction reaction because phosphorous in P³⁻ in K₃P oxidizes to P⁵⁺ in K₃PO₄ and oxygen reduces.
(f) 
This is acid base reaction because there is no change of oxidation state on either side of the reaction.