The correct answer should be A.Ca and Br. A salt consists of a metal and a nonmetal, and a positive and negative charge. Ca (Calcium) is a metal and Br (Bromine) is a nonmetal, Ca is a +2 charge and Br is a -1 charge, so this is the only correct answer. Hope this helps :)
The last choice is the equation for photosynthesis
Explanation :
(a) 
This reaction is combustion reaction in which an oxygen react with a molecule to give its corresponding oxides ans water molecule.
(b) 
This reaction is a redox reaction or oxidation-reduction reaction in which sulfur get oxidized and oxygen get reduced.
(c) 
This reaction is a combination reaction in which the two reactants molecule combine to form a large molecule or product.
(d) 
This reaction is a decomposition reaction in which a large molecule or reactant decomposes to give two or more molecule or products.
(e) 
This reaction is a double displacement reaction in which the cation of two reactants molecule exchange their places to give two different products.
(f) 
This reaction is a combination reaction in which the two reactants combine to form a large molecule or product.
(g) 
This reaction is a double displacement reaction in which the cation of two reactants molecule exchange their places to give two different products.
(h) 
This reaction is combustion reaction in which a hydrocarbon react with an oxygen to give carbon dioxide and water as a products.
Answer:
More than three decade the temperature of earth is increasing equally by the rate of 0.8 Celsius (1.4 Fahrenheit). It is going to be very harmful for the human being as well animals. The global warming is the main reason and hole in the ozone layer had been the cause of increasing the temperature of the earth. Humans are also involved in cause in temperature of earth by cutting forests and making land suitable for residence and not planting more trees instead of the cut trees.
Answer is b. Hope it help