The correct answer is: A. As, as.
The sentence “The more you earn, the more you can spend” is an example of a proportional relationship. In a proportional relationship, there is a direct relationship between two quantities, such that if one quantity increases, the other quantity also increases. In this case, the two quantities are the amount of money you earn and the amount of money you can spend. The more money you earn, the more money you can spend.
The other options are incorrect because they do not accurately describe the relationship between the two quantities. Option B, “The, the,” is incorrect because it does not indicate a direct relationship. Option C, “If, than,” is incorrect because it implies that there is a conditional relationship, where one quantity only increases if the other quantity also increases. Option D, “So, as,” is incorrect because it implies that there is a causal relationship, where one quantity causes the other quantity to increase.
In conclusion, the correct answer to the question “. . . . . more you earn, . . . . . . more you can spend” is A. As, as.