Plz explain me this question

Dear student,
Please find below the answer:

A vehicle is a kind of thing used to transport goods and people. Chromosomes do the same job in case of heredity.

Chromosomes are known hereditary vehicles because they contain genes which carry the heredity characteristics from the parents to the child. Chromosomes are the hereditary material because they contain genes. They transfer the character of parents to their offspring. 

Hope this clears your doubt.
Regards.