Whet is his (her,their) job?

❅ When referring to more than one person, like a group, you will do "their" job.
❅ When referring to only one person, it will be his/her
❅ When saying for a girl it will be labeled as Her
❅ When for a boy, as His. 

b.It presents information using a common structure.

Expository writing, which is informative by nature, will always contain certain elements, and these elements are characteristic of how an expository piece is organized (or structured).  All expository writing will contain a main idea, support, then a conclusion.  And, this organization (or structure) is, again, common to all types of expository writing.