The correct answer is: A. hook bolts
Hook bolts are a type of fastener that is used to secure sleepers to the top flange of a girder. They are made of steel and have a curved head that fits over the top of the sleeper. The bolt is then driven through the sleeper and into the girder, where it is secured with a nut.
Dog spikes are a type of fastener that is used to secure sleepers to the base of a girder. They are made of steel and have a pointed end that is driven into the ground. The spike is then bent over to secure the sleeper in place.
Fang bolts are a type of fastener that is used to secure sleepers to the base of a girder. They are made of steel and have a curved head that fits over the top of the sleeper. The bolt is then driven through the sleeper and into the ground, where it is secured with a nut.
Rail screws are a type of fastener that is used to secure rails to sleepers. They are made of steel and have a threaded shank that is driven into the sleeper. The screw is then secured with a nut.
Hook bolts are the most common type of fastener used to secure sleepers to girders. They are easy to install and provide a secure connection.