Why is an article written about a famous explorer considered a secondary source

Athief was passing by a house under construction when he noticed that the ladder being used by workers on the roof had copper braces supporting the rungs. after making sure that the workers on the roof could not see him, the thief used pliers that he had in his pocket to remove all of the copper braces that he could reach from the ground. a short time later, a worker climbed down the ladder and it collapsed. he fell to the ground and severely injured his back. the thief was apprehended a few hours later trying to sell the copper for scrap. a statute in the jurisdiction makes it a felony for "maliciously causing serious physical injury to another." the thief was charged with malicious injury under the statute and was also charged with larceny. after a jury trial in which the above facts were presented, he was convicted of both charges. if he appeals the conviction for the malicious injury charge on grounds of insufficient evidence, how should the court rule? a affirm the conviction, because the thief was engaged in criminal conduct at the time of the act that resulted in the injury. b affirm the conviction, because the jury could have found that the thief acted with malice. c reverse the conviction, because there was no evidence that the thief intended to injure anyone. d reverse the conviction, because there was no evidence that the thief bore any malice towards the workers on the roof.