Which of the following is a reasonable way to select the number of principal components \"k\"?

- Choose k to be the smallest value so that at least 99% of the varinace is retained
- Choose k to be 99% of m (k = 0.99*m, rounded to the nearest integer).
- Choose k to be the largest value so that 99% of the variance is retained.
- Use the elbow method.

Correct Answer: