Step 1: Understanding the question.
Manju is searching for the FPO (Food Processing Organization) mark, which is a certification for food products.
Step 2: Analyzing the options.
- Pickle jar: This is a food product, and it would carry the FPO mark to show that it meets food safety standards.
- Shirt: A shirt would not carry an FPO mark, as it is a non-food item.
- Bulb: A bulb is a non-food product and would not have an FPO mark.
- Gold necklace: This is jewelry, not a food product, so it would not carry the FPO mark.
Step 3: Conclusion.
The product Manju is looking at is most likely a Pickle jar, as it would be certified with the FPO mark.
Final Answer:
\[
\boxed{\text{The correct answer is (1) Pickle jar.}}
\]