Determine which of the following are observational studies? Which are experiments? I. sixth-grade students are randomly divided into two groups. One group is taught math using traditional techniques; the other group is taught math using a reform method. After one year, each group is given an achievement test to compare its proficiency with that of the other group. II. A poll is conducted in which 500 people are asked whom they plan to vote for the upcoming election. III. A survey is conducted asking 400 people, "Do you prefer Coke or Pepsi" IV. A study to determine whether there is a relation between the rate of cancer and an individual's proximity to high-tension wires. V. While shopping, 100 people are asked to perform a taste test in which they drink from two unmarked cups. They are then asked which drink they prefer. Group of answer choices I, V are experiments; II, III, IV are observational studies II, III, IV are experiments; I, V are observational studies I, II, III are experiments; IV, V are observational studies I, IV, V are experiments; II, III are observational studies I, II, III are observational studies; IV, V are experiments