Read the following statements :-
(A) Characters are controlled by same units called factors
(B) In an dissimilar pair of factor one member dominates the other
(C) The law of dominance is used for explain the expression of only one parents in `F_(2)`
(D) Factors occors in pairs
Which of the above statements explain Mendel's law of dominance ?

Options

A. Only A
B. Only B & d
C. A, B, C, D
D. Only A & B

Answer

To determine which statements explain Mendel's Law of Dominance, let's analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement (A)**: "Characters are controlled by the same units called factors."
- This statement is partially correct but not specific to Mendel's Law of Dominance. In Mendelian genetics, the term "factors" refers to what we now call alleles. However, this statement does not directly explain the concept of dominance.

**Hint**: Consider the terminology used in genetics; "factors" is an older term that has been replaced by "alleles."

2. **Statement (B)**: "In a dissimilar pair of factors, one member dominates the other."
- This statement accurately reflects Mendel's Law of Dominance. It explains that when two different alleles (factors) are present, one (the dominant allele) can mask the expression of the other (the recessive allele).

**Hint**: Think about how dominant and recessive traits interact in a heterozygous condition.

3. **Statement (C)**: "The law of dominance is used to explain the expression of only one parent in F2."
- This statement is incorrect. Mendel's Law of Dominance does not limit the expression to only one parent. In fact, both parents contribute alleles, and the dominant allele will express itself in the offspring.

**Hint**: Recall how both parental traits can be observed in the offspring depending on their dominance.

4. **Statement (D)**: "Factors occur in pairs."
- This statement is also true and is consistent with Mendel's findings. Mendel proposed that alleles exist in pairs, and this is foundational to understanding how traits are inherited.

**Hint**: Consider how alleles segregate during gamete formation.

### Conclusion:
Based on the analysis:
- **Correct Statements**: (B) and (D) explain Mendel's Law of Dominance.
- **Final Answer**: The statements that explain Mendel's Law of Dominance are **(B) and (D)**.