Which of the following statements about pooling are true? i. in statistics, to pool is to create an estimate of a common variance for two samples. pooling gives narrower confidence intervals and lower p-values, so it yields a more precise final result with a higher power of the test. ii. pooling can only be used in the rare instances when you can assume the populations are of equal size. iii. without requiring that strong and often unrealistic conditions be met, computer software (or a calculator) will give a final result without pooling that's nearly as precise as the result you'd get if you pooled. iv. you can use pooling when the sample standard deviations are the same. a. i only b. ii only c. i and iii only d. ii and iv only e. i, ii, and iii only