Question

__________ is a three-dimensional, 20-sided figure with 12 evenly spaced corners

○ helical capsid

○ icosahedral capsid

○ rod

○ capsid

Explanation:

To solve this, we analyze each option:

• Helical capsid: Has a helical (spiral) structure, not 20 - sided with 12 corners.
• Icosahedral capsid: By definition, an icosahedron is a three - dimensional figure with 20 triangular faces, 12 vertices (corners) that are evenly spaced.
• Rod: A rod - shaped structure doesn't match the 20 - sided, 12 - cornered description.
• Capsid: Is a general term for the protein shell of a virus, not a specific structure with the given geometric properties.

Answer:

B. Icosahedral capsid