8. In machine learning, an early-stopping task is performed at the following phase: a. training b. testing c. validation d. evaluation 9. If a data set has the indices {1, 2, 3, 4, 5) for 5 observations, then which of the following are possible bootstrap samples to be used for a machine learning technique? a. 5, 2, 1, 4,3 b. 2, 2, 1, 3, 3, 4 a. 5, 1, 6, 3,3 b. 2,2,5,4,4 10. This quality measure should not be used if the data is imbalanced, which one is it? a. accuracy b. precision c. sensitivity d. specificity 11. Which big data controller is the contributor to sparsity problem? a observations b. features c. labels d. subspace