According to Chargaff's rule, which one is correct?

Q. In the case of double-stranded DNA, which of the following base ratios are always equal to one?
a. $(A+T)/(G+C)$
b. $(A+G)/(C+T)$
c. $C/G$
d. $(G+T)/(A+C)$
Select the correct answer.

Q. The following sequence contains the open reading frame of a polypeptide. How many amino acids will the polypeptide consist of?
5' A G C A T A T G A T C G T T T C T C T G C T T T G A A C T A - 3'

Q. The complementary strand for the following single strand of DNA is:
$5^{\prime }\leftarrow A-T-G-C-T\to 3^{\prime }$

Q. During analysis of the DNA of an organism having $5386$ nucleotides find out A$=29\%$, G$=17\%$, C$=32\%$, T$=17\%$. Considering the Chargaff's rule it can be concluded that

Q. The restriction enzyme responsible for the cleavage of following sequence is
5' - G - T - C - G - A - C - 3'
3' - C - A - G - C - T - G - 5'