Why are media potentially so effective? A. People spend more than half of their time interacting with media.
B. Over the last 10 years, the number of people over the age of 50
who use the Internet has increased.
C. Search engines are growing in number, helping more and more
people find what they're looking for online.
D. All of the above

radiant energy is a form of kinetic energy only.(a)

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.

you answered your own : -/