T-even bacteriophages look like tadpoles with a distinct head and tail.
This structure is categorized under "complex symmetry" because it combines both helical and polyhedral shapes.
Step 1: Lock in two matches from known virus structures. Bacteriophages such as the T-even phages have a complex structure, an icosahedral head joined to a helical tail, so that item pairs with the complex category. The measles virus is an enveloped virus studded with glycoprotein spikes, so that item pairs with the spike category. Step 2: Use these two anchors to eliminate wrong options. Any option that breaks either of these two pairings can be ruled out immediately. Step 3: Settle the remaining two items by symmetry. Plant viruses like the tobacco mosaic virus show simple helical symmetry, while many animal viruses without a complex tail, such as adenovirus, show icosahedral symmetry, which fixes the last two matches. Final answer: Option 1, A-IV, B-II, C-I, D-III.
