You did not include the diagram, but the answer is very easy to figure out. The mRNA base that will go in location 1 depends on the DNA base in location 1:
If the DNA base is Adenine (A), the mRNA base will be Uracil (U)
If the DNA base is Thymine (T), the mRNA base will be Adenine (A)
If the DNA base is Cytosine (C), the mRNA base will be Guanine (G)
If the DNA base is Guanine in (G), the mRNA base will be Cytosine (C)