Interaction design is a process for designing interactive to support the way people communicate and interact in their everyday and working lives.
select one:
a. softwares
b. systems
c. products
d. machines

Product

Explanation:

Interaction design is a practices of designing interactive digital products and services in such a way it perfectly or closely mimic the way humans communicate and interact in real life scenario. or it can be rephrased as creating a user experiences that augment the way people work, communicate and interact.

interaction design sometimes goes beyond just creating digital products it also useful when creating physical ones.

answer; availability;

the major difference between the two is the objective and the reward of the game. candy crush has a puzzle theme with the objective of meeting a specific quota of points or objects, you are able to gain access to the next level and compete with peers on the process. on duolingo the objective is rather different, you are given sets of questions for you to answer for you to move to the next level and as for the reward, you are able to learn available language as this is an app developed to teach the user about other languages.