Why are unsolicited application letters more challenging to write than solicited application letters?

a. Nobody wants to receive unsolicited application letters. 

b. With an unsolicited letter, you have to do the research to identify the qualities the company would likely be looking for and convince someone to consider you for a job that might not even be open yet.

c. Solicited application letters are shorter, making it more likely than recruiters will bother to read them.

d. Unsolicited letters do not lend themselves to the AIDA model.