After the completion of biosynthetic stage in a bioreactor, the product undergoes a series of processes before it is ready for marketing. List of the processes is given below. Identify the option that gives the correct sequence of the processes carried out :

(i) Purification of product

(ii) Formulation with suitable preservative

(iii) Separation of product

(iv) Clinical trial of product

The correct option is (iii) → (i) → (ii) → (iv).

After the completion of the biosynthetic stage inside a bioreactor, the resulting harvest is a complex mixture containing cell debris, culture medium, and various metabolic byproducts along with the desired product. The series of processes required to recover, purify, and prepare this product for commercial use is collectively known as downstream processing. The logical sequence of these steps is detailed below:

1. Separation of product (iii):
The first step in downstream processing is to isolate the target product from the bulk biomass. This is typically achieved through physical separation methods such as filtration or centrifugation to remove solid cell debris and intact cells from the liquid medium containing the product.

2. Purification of product (i):
Once the crude product is separated, it remains contaminated with other soluble proteins, nucleic acids, and media components. It must undergo purification steps—such as chromatography, precipitation, or ultrafiltration—to isolate the target molecule at a high level of purity.

3. Formulation with suitable preservative (ii):
After achieving the required purity, the product is formulated. This involves mixing the active ingredient with suitable preservatives, stabilizers, or buffers to maintain its activity, stability, and shelf-life during storage and distribution.

4. Clinical trials of product (iv):
For biopharmaceuticals and medical products, the formulated product must undergo strict quality control testing and clinical trials to demonstrate safety, dosage tolerance, and efficacy in humans before it receives regulatory approval and is marketed.

Therefore, the correct biological and chemical processing sequence is (iii) → (i) → (ii) → (iv).