What important question do the various research techniques lack the ability to answer?

What important question do the various research techniques lack the ability to answer? Did consumers purchase the product because of viewing the producers ads?

Besides asking, where did you find out about us, it is very hard for a research team to use techniques to find out if they viewed the companies ad's before making the purchase. It's hard to know if they saw and actually watched the commercial on T.V. or if they read about it in the magazine on purpose. 

answer; /// i do believe that the correct answer is (d) cooperative play; /// good luck

well, paralell is parallel. i am providing links to .

hope this !

a series circuit is one with all the loads in a row. there is only one path for the electricity to flow. if this circuit was a string of light bulbs, and one blew out, the remaining bulbs would turn off.

unlike in series circuits, a charge in a parallel circuit encounters a single voltage drop during its path through the external circuit. the current through a given branch can be predicted using the ohm's law equation and the voltage drop across the resistor and the resistance of the resistor.

a parallel circuit has certain characteristics and basic rules: a parallel circuit has two or more paths for current to flow through. voltage is the same across each component of the parallel circuit.