Adc voltmeter may be used directly to measure a) frequency b)polarity c) power factor d) power

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.  

b. a lightning bug, plug of grass, and a worm