Encapsulation matrices for producing synthetic seeds (e.g., sodium alginate–CaCl2 gels) are typically:

Introduction / Context:
Encapsulation protects somatic embryos and allows handling similar to seeds. The physical chemistry of the gel determines water retention, gas exchange, and mechanical strength of synthetic seeds.

Given Data / Assumptions:

• Common hydrogels include alginate crosslinked with calcium, carrageenan, and other polysaccharides.
• Gels must be stable in aqueous environments yet permeable to water and solutes.
• Somatic embryos are living and require moisture and oxygen.

Concept / Approach:
Calcium alginate forms a crosslinked polymer network that is insoluble in water but swells to form a hydrogel. This provides mechanical protection and a hydrated microenvironment while preventing the bead from dissolving during handling or sowing.

Step-by-Step Solution:

Verification / Alternative check:
Standard encapsulation protocols drop alginate–embryo suspensions into CaCl2 baths to instantly form insoluble gel beads that are then rinsed and stored.

Why Other Options Are Wrong:

• A: If soluble, beads would dissolve during sowing or culture.
• B/D/E: Not representative of hydrogel behavior required for synthetic seeds.

Common Pitfalls:
Confusing swelling with solubility; hydrogels can absorb water while remaining insoluble.

Final Answer:
Insoluble in water (hydrogel network that retains integrity)