Which is a requirement for natural selection to occur? heritable variations for some traits
the ability of an organism to improve a trait during its lifetime
equal probability of survival for all offspring
fewer offspring than the environment can support

the cover letter for a job search includes the skills one has for the particular job. including a cover letter is always a good idea, as it describes the ability to perform a task, and the employer can easily fetch the intention of the job you want to do.  

the cover letter is very important to be included in the job search document. hence, i strongly with the statement.  

label a.   prophase

label b. metaphase

label c: anaphase

label d: telophase