Zack is a welder and is contracted to build oil tanks. Zack was doing well, but then there was an accident in the workplace that caused a part of the oil tank to fall off and injure another worker's legs. The worker sued Zack because he was the one responsible for welding the oil tank that fell off. Over the review, they notice that Zack's welding wasn't fully welded into the metal per the contract and as per industry standard, which caused the oil tank to fall off. Did Zack commit negligence