Retraining is required at intervals of or less.

a)

6 months

b)

18 months

c)

3 years

d)

6 years

Retraining is required at intervals of 6 months or less.

A)  6 months

Explanation:

Retraining can be defined as the process of making employees aware of the new technologies, strategies, and getting them a hands-on approach so that they can incorporate them into their allotted work.

For the healthy and smooth functioning of an enterprise, retraining should be done in after short intervals of time like six months.

Retraining ensures that the employees not only are aware of new inventions, but they are also able to follow the trends of the market and retraining also allows them to test their current knowledge and application of acquired skills.

that would be my answer.