Students were asked to give a guess about a unicellular organism with darkly stained nucleus. Which of the following can be straight away excluded from the list:

Explanation

Lactobacillus is a genus of bacteria, and bacteria do not have nuclei in the same way that eukaryotic cells (such as protists) do. Bacterial genetic material is contained within a region called the nucleoid, which is not membrane-bound and does not exhibit the same dark staining characteristics as eukaryotic nuclei. Since Lactobacillus is a bacterium and not a unicellular organism with a darkly stained nucleus, it can be excluded from the list.