Final answer:
The most efficient method to compare multiple fractions is by finding common denominators and comparing the numerators. This allows for easy comparison without the complexity of dealing with decimals or the inefficiency of cross-multiplication.
Step-by-step explanation:
The best way to compare the size of multiple fractions is option (B) Common denominators. By converting each fraction to have a common denominator, you can directly compare the numerators to determine which fractions are larger or smaller. For instance, to compare 1/3 and 1/4, you could convert them to 4/12 and 3/12, and it's clear that 4/12 (which is 1/3) is larger.
Option (A) Cross-multiplication, is a method used to compare two fractions by cross-multiplying the numerators with the opposite denominators, but this becomes less efficient with multiple fractions. Option (C) Converting to decimals, can also be used, but it may not always result in an exact value due to repeating decimals, making comparisons more difficult. Option (D) Adding fractions, is irrelevant for comparing the sizes of fractions.