Which of the following organisms is/are correctly assigned to its/their taxonomic group?

Consider the following statements $(A-D)$:
$(A)$ Heterocysts are important sites for nitrogen fixation in $\text{BGA}$.
$(B)$ Cell wall of diatoms is indestructible due to presence of calcium carbonate.
$(C)$ In fungi,the cell wall is made up of chitin.
$(D)$ Algae show isogamous,anisogamous,and oogamous types of sexual reproduction.
How many of the above statement$(s)$ is/are not correct?

Select the correct match with respect to Whittaker's system of classification.

Select the correct option for natural systems of classification.

Differentiate between the three domains of life.

Which of the following lacks a cell wall?