As we go from species to kingdom in a taxonomic hierarchy, the number of common characteristics

1.  will decrease

2.  will increase

3.  remain same

4.  may increase or decrease

(a) Lower the taxa, more are the characteristic that the members within the taxon share. So, lowest taxon share the maximum number of morphological similarities, while its similarities decrease as we move towards the higher hierarchy,i.e., class, kingdom. Thus, rest of the option are incorrect.