I have been studying present perfect tense this week and I tried so many exercises to improve my grammar. Then I have tried this exercise. But I can't interpret the correct answer for the 1st question. I thought the correct answer for the question no 1 is.
you have been keeping a pet for 3 years.
But according to the website correct answer is
You've kept a pet for three years.
Please explain the answer for using present perfect simple instead of using present perfect continuous.