In football, he was recruited by Alabama, Georgia, and Oklahoma, all of whom were willing to break the color barrier just for Jackson (Oklahoma had black football players before 1964- including Prentice Gautt, a star running back recruited in 1957, who played in the NFL with the St. Louis Cardinals). Jackson declined Alabama and Georgia because he was fearful of the South at the time, and declined Oklahoma because they told him to stop dating white girls. For baseball, Jackson was scouted by Hans Lobert of the San Francisco Giants who was desperate to sign him. The Los Angeles Dodgers and Minnesota Twins also made offers, and the hometown Philadelphia Phillies gave him a tryout but declined because of his "hitting skills". His father wanted his son to go to college, where Jackson wanted to play both football and baseball. He accepted a football scholarship from Arizona State University in Tempe; his high school football coach knew ASU's head football coach Frank Kush, and they discussed the possibility of his playing both sports. After a recruiting trip, Kush decided that Jackson had the ability and willingness to work to join the squad. One day after football practice, he approached ASU baseball coach Bobby Winkles and asked if he could join the team. Winkles said he would give Jackson a look, and the next day while still in his football gear, he hit a home run on the second pitch he saw; in five at bats he hit three home runs. He was allowed to practice with the team, but could not join the squad because the NCAA had a rule forbidding the use of freshman players. Jackson switched permanently to baseball following his freshman year, as he did not want to become a defensive back. To hone his skills, Winkles assigned him to a Baltimore Orioles-affiliated amateur team. He broke numerous team records for the squad, and the Orioles offered him a $50,000 signing bonus if he joined the team. Jackson declined the offer stating that he did not want to forfeit his college scholarship. In the beginning of his sophomore year in 1966, Jackson replaced Rick Monday (the first player ever selected in the Major League Baseball draft and a future teammate with the A's) at center field. He broke the team record for most home runs in a single season, led the team in numerous other categories and was first team All-American. Many scouts were looking at him play, including Tom Greenwade of the New York Yankees (who discovered Mickey Mantle), and Danny Murtaugh of the Pittsburgh Pirates. In his final game at Arizona State, he showed his potential by being only a triple away from hitting for the cycle, making a sliding catch, and having an assist at home plate. Jackson was the first college player to hit a home run out of Phoenix Municipal Stadium.

Answer this question "Why did he chose baseball over football" by extracting the answer from the text above.
Winkles said he would give Jackson a look, and the next day while still in his football gear, he hit a home run on the second pitch he saw;