Which of the following cells does not contain a nuclear membrane?

Which of the following statements is correct for archaea?

Cyanobacteria and heterotrophic bacteria have been clubbed together in eubacteria of kingdom-Monera as per the 'five kingdom classification' even though the two are vastly different from each other. Is this grouping of the two types of taxa in the same kingdom justified? If so,why? Discuss the cellular composition of cyanobacteria and heterotrophic bacteria that make them introduced in eubacteria.

Provide the full names for the following abbreviations:
$(1)$ $MLO$
$(2)$ $VAM$

Organisms known as methanogens are found in abundance in ............ .

Which of the following is the smallest living cell and can live without oxygen?