A: Disease or infections which are transmitted through sexual intercourse are collectivley called sexually transmitted diseases.
R: STDs if not properly treated may lead to pelvic inflammatory diseaes, absorption, still birth, estopic pregnancies, infertility or even cancer of reproductive tract.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reasons is not the correct expalanation of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4).

Answer

### Step-by-Step Solution

1. **Understanding the Assertion (A)**:
- The assertion states that diseases or infections transmitted through sexual intercourse are collectively called sexually transmitted diseases (STDs).
- This is a factual statement, as STDs are indeed defined as infections that are primarily spread through sexual contact.

2. **Understanding the Reason (R)**:
- The reason explains that if STDs are not properly treated, they can lead to serious health issues such as pelvic inflammatory disease, abortion, stillbirth, ectopic pregnancies, infertility, or even cancer of the reproductive tract.
- This statement is also true, as untreated STDs can have severe consequences on reproductive health.

3. **Evaluating the Relationship Between A and R**:
- While both the assertion and the reason are true, the reason does not directly explain the assertion. The assertion defines what STDs are, while the reason discusses the potential consequences of untreated STDs.
- Therefore, the reason is not a correct explanation of the assertion.

4. **Conclusion**:
- Since both the assertion and reason are true but the reason does not explain the assertion, the correct answer is:
- **Option 2**: Both assertion and reason are true, but the reason is not a correct explanation of the assertion.