According to the Chargaff's rule, "The ratios between Adenine (A) and ................ and Guanine (G) and ................... are constant and equal to one in a double-stranded DNA."
a) Thymine, Cytosine
b) Cytosine, Thymine
c) Lysine, Arginine
d) Arginine, Lysine

Options

A. Thymine, Cytosine
B. Cytosine, Thymine
C. Lysine, Arginine
D. Arginine, Lysine

Explanation

**Step-by-Step Solution:**

1. **Understanding Chargaff's Rule**: Chargaff's rule states that in double-stranded DNA, the amount of adenine (A) is equal to the amount of thymine (T), and the amount of guanine (G) is equal to the amount of cytosine (C). This can be summarized as A = T and G = C.

2. **Identifying the Ratios**: According to the rule, the ratios between adenine and thymine, and guanine and cytosine are constant and equal to 1. This means that for every adenine, there is one thymine, and for every guanine, there is one cytosine.

3. **Filling in the Blanks**: The question asks to fill in the blanks: "The ratios between Adenine (A) and ................ and Guanine (G) and ................... are constant and equal to one in a double-stranded DNA." Based on Chargaff's rule, we fill in the blanks with thymine (T) and cytosine (C) respectively.

4. **Final Answer**: Therefore, the complete statement according to Chargaff's rule is: "The ratios between Adenine (A) and Thymine (T) and Guanine (G) and Cytosine (C) are constant and equal to one in a double-stranded DNA."

5. **Choosing the Correct Option**: From the provided options, the correct answer is:
a) Thymine, Cytosine