A daily glass of pomegranate juice can improve your memory and concentration. Which evidence below would be the most credible to support this claim?

An article on healthy eating in the current issue of Self magazine.

The trainer at your gym.

An ad by the Pomegranate Growers Association.

A 2013 preliminary study at UCLA on the effect of antioxidants found in pomegranates on memory.

Read this excerpt from i never had it made. "it's all that ought to count," he replied. "but it isn't. maybe one of these days it will be all that counts. that is one of the reasons i've got you here, robinson. if you're a good enough man, we can make this a start in the right direction. but let me tell you, it's going to take an awful lot of courage." he was back to the crossroads question that made me start to get angry minutes earlier. he asked it slowly and with great care. "have you got the guts to play the game no matter what happens? " "i think i can play the game, mr. rickey," i said. the next few minutes were tough. branch rickey had to make absolutely sure that i knew what i would face. beanballs would be thrown at me. i would be called the kind of names which would hurt and infuriate any man. i would be physically attacked. could i take all of this and control my temper, remain steadfastly loyal to our ultimate aim? which is the central idea of this excerpt?