Blood vessels that have thinner walls that are more likely to collapse when blood is withdrawn during a venipuncture are called:

The answer is; veins

Smaller veins are prone to collapsing during venipuncture than larger veins. Due to the suction force created by the needle syringe, the higher outer pressure may cause the walls of the veins to collapse. Once collapsed, the inflamed walls are hard to recover. This stops the flow of blood through the veins. However, the body forms new smaller veins.  

thats not even an aswer choice

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.