The drop down options are "observational study" or "experiment". Please choose one for each

For each of the following, state whether it is an observational study or an experiment: a) From December 2007 through March 2012, researchers at the University of Pittsburgh studied a new medication to treat osteoporosis in frail elderly women. The researchers administered a daily dose of the medication or a placebo by injection along with calcium and vitamin D supplements. Then the researchers measured the hip and spine bone density of each patient at 12 and 24 months. Results were published in the Journal of the American Medical Association (JAMA) in April 2015. [ Select] - v b) Educational psychologists investigate the impact of different types of instruction on learning. In one study, researchers taught a math lesson to 9th-graders using the "Inventing to Prepare for Learning llPL)" instructional cycle. A second group of students received traditional "tell and practice\" instruction. After the lessons, both groups studied a worked example of a math problem on their own. Then they took a test that included problems like the worked example. The journal Cognition and instruction published the results in 2004. [59'9\"] V' c) In June 2011 The Washington Post published the results of a poll about the war in Afghanistan. In the poll 1,502 U.S. adults answered the question, "Do you think the U5. made the right decision or the wrong decision in using military force in Afghanistan?"j [55'3\"] V d) Over a 17~year period researchers studied a sample of 707 individuals from a single community. They recorded the number of hours each individual spent watching television during adolescence and early adulthood. In later years, they recorded the number of aggressive acts by individuals in the study. Science magazine published the results in 2002 in an article titled "Televisionyiewing and Aggressive Behavior during Adolescence and Adulthood\