Please do this
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Dear student,
Please find below the answer:

1. The correct option is (c). Viruses are neither living nor non-living. They are borderline organisms.
2. The correct option is (a). Sour milk gets converted to curd by Lactobacillus which is a bacteria.
3. The correct option is (d). Carbon dioxide given off during the fermentation of sugar makes bread soft and fluffy.
4. The correct option is (b). Viruses do not have a regular cell structure.
5. The correct option is (c). Algae can be unicellular or multicellular.
6. The correct option is (a). Lactobacillus is useful in making cheese.

Hope this clears your doubt.
Regards.