Reproduction is possible between two members of which taxonomic category?

What is the taxonomic category formed by a group of related genera?

Four statements are given below regarding the nomenclature of organisms. Which two statements are correct?
$(1)$ The first name denotes the species and the second denotes the genus.
$(2)$ $A$ species name used for one organism cannot be used for another organism.
$(3)$ Each word in a handwritten scientific name must be underlined.
$(4)$ It is mandatory to write the sub-species name after the species name for every organism.

What different criteria would you choose to classify people that you meet often?

In which of the following pairs of categories is it more difficult to determine the relationship to other taxa at the same level,thus making the problem of classification more complex?

In taxonomy,the category 'Class' is placed between which of the following?