The answer to this should be B. Worm. A pinion is a the smallest gear out of the listed ones above. spur would be next then wheel and the biggest if them all would be the spur. I'm not completely sure if my answer is 100% correct, but I feel confident enough about it. Hope this helps. :)
        
                    
             
        
        
        
I have concluded the answer is a
        
                    
             
        
        
        
Answer:
It is not valid
Explanation:
I'll assume the question relates to cell referencing in Microsoft Excel.
To reference a cell in Excel, we make use of the following steps:
- Write out the cell column name first
- Followed by the row number
7b implies that, the row number first, followed by the column name; this doesn't follow the naming convention of cells. 
Hence, 7b is invalid.
 
        
             
        
        
        
<span>Barricades, vertical panels, drums, and cones in construction zones are known as channelizing devices. They a</span>re used in construction and maintenance work areas <span> to notify drivers or passengers of unusual or potentially dangerous conditions in or near work areas.
</span>A barricade is a portable or fixed device having from one to three rails with appropriate markings. It is used to control traffic by closing, restricting, or delineating all or a portion of the right-of-way.<span>Drums are most commonly used to channelize or delineate traffic flow but may also be used singly or in groups to mark specific locations.</span>
        
             
        
        
        
privilege to operate a motor vehicle-drivers License
Able to get when 15. Valid for 1 yr. Allows you to drive with a parent in the car. $15. Bring social security and birth certificate to the DLD. Have for 6 months (and do 40 hrs) before getting license.-Learner Permit