A.  they have a higher proportion of adenine–thymine than guanine–cytosine base pairs.
The option A represents the complete opposite of "high-gc gram-positive bacteria". High GC content means that this bacteria have more guanine ans more cytosine than the other base pairs- adenine–thymine. This means all the other options are correct.
        
             
        
        
        
DNA polymerase moves along the old strand in the 3'-5' direction, creating a new strand having the same 5'-3' direction.
 
        
             
        
        
        
Answer:
A 
Explanation:
I think an untreated water can carry disease causing organisms and make people sick