Most of the Professional Bloggers use WordPress as their choice of platform for self hosting blogs. WordPress is so popular that almost 20 to 25 percent of total web sites uses it. WordPress gives us many features and options to make our blog posts SEO friendly. Permalinks are introduced from WordPress 3.0, which lets us customize the permalink structure. Category in WordPress Permalink plays important role in SEO of the post. It is better to select which category goes in to URL of the blog post.
We generally use %category% as a tag in post permalink structure. WordPress selects category with lowest ID by default for permalink if you select more than one category for a post, which is not practical for SEO optimization. We need a solution which let us select the category of our choice for post permalink category tag, and here is the one.
Plugin for choosing Category in WordPress Permalink
Hikari Category Permalink plugin for WordPress allows post authors to choose which category is used for post permalink %category% tag. This plugin allows to choose category for each post separately while editing of the post. This plugin is not rewrite of URL rules.
Install Hikari Category Permalink plugin and activate it. That’s it, now you can choose the category for permalink. 
While in post editor place your mouse cursor on the category which you want to select for permalink, you will see “Permalink” next to it, just click on the link, the category will be in bold now. Now save the post, the category for permalink is changed to the one which you selected.
The plugin is last updated 2 years back, its working fine in latest WordPress version 4.4.2.
Let us know which solution you are using to get this option or is this the option you are looking for?