Pedigree analysis is useful in human genetics because :

Options

A. It can trace the inheritance of a particular trait
B. Control crosses can not be performed in human beings
C. It helps to trace disease in a family
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding Pedigree Analysis:**
- Pedigree analysis is a graphical representation of a family's genetic history. It is often depicted as a family tree that illustrates the inheritance patterns of specific traits or genetic disorders across generations.

2. **Importance of Pedigree Analysis in Human Genetics:**
- It helps in understanding how traits or disorders are passed from one generation to the next. By analyzing the pedigree, geneticists can identify patterns of inheritance, which is crucial for diagnosing genetic conditions.

3. **Evaluating the Options:**
- The question provides four options regarding the usefulness of pedigree analysis in human genetics. We need to evaluate each option to determine their validity.

4. **Option 1: Tracing Inheritance of a Trait**
- This statement is true. Pedigree analysis allows us to trace the inheritance of specific traits through generations, helping to identify whether a trait is dominant, recessive, or linked to sex chromosomes.

5. **Option 2: Control Crosses in Humans**
- This statement is also true. Unlike model organisms such as pea plants, controlled genetic crosses cannot be performed in humans due to ethical considerations and the complexity of human genetics. Therefore, pedigree analysis becomes a vital tool for studying inheritance patterns.

6. **Option 3: Tracing Disease in a Family**
- This statement is true as well. Pedigree charts are instrumental in tracing the occurrence of genetic disorders within a family, helping to identify carriers and affected individuals.

7. **Conclusion:**
- Since all three options are true, the correct answer to the question is the fourth option, which states that all of these reasons contribute to the usefulness of pedigree analysis in human genetics.

**Final Answer:**
- Pedigree analysis is useful in human genetics because it can trace the inheritance of a particular trait, control crosses cannot be performed in humans, and it helps to trace disease in a family. Therefore, the correct answer is: **All of these.**

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