No lines on the hex head of a Bolt indicates it is what grade? Grade 2 Grade 8 Grade 5

## Step 1<br />The problem is asking about the grade of a bolt based on the absence of lines on its hex head. The grade of a bolt refers to its strength and durability, which is determined by the material and manufacturing process used to produce it.<br />## Step 2<br />In the United States, the grade of a bolt is indicated by the presence or absence of lines on the hex head. A bolt with no lines on its hex head is typically a Grade 5 bolt.<br />## Step 3<br />Grade 5 bolts are made from medium carbon steel and are designed to handle high tensile strength. They are commonly used in applications where high strength is required, such as in construction and engineering.