Answer:
B
Explanation:
All the other answers are either too frequent or provide a long testing usability time for no reason. If you were to publish a digital product the only real testing time needed is half a day or less. To prevent spam, once a month would also be applicable.
The best frequency with which to test usability with users is B. monthly for half a day.
The testing time needs to be frequent enough that errors are detected, but not too frequent that it disturbs users.
The best frequency would therefore be once a month. The duration should also not inconvenience users so half a day is fine.
In conclusion, option B is correct.
Find out more on system testing at https://brainly.com/question/25594630.