Apostrophe Catastrophe!

One of the most common errors in writing is using the apostrophe incorrectly in plurals and possessives. I received an email from one consultant whose lines I quote here: In addition, I personally conduct coaching and mentorship programs for senior executives, managers and CEO's.
This gentleman has used an apostrophe for a plural. Could be a careless mistake or he simply got confused!
A couple of things to remember while using the apostrphe:

• Use an apostrophe to indicate possession. Example:

The dog's kennel is in the garden. The apostrophe is before the s when you are writing about one dog. (Singular possessive)

The dogs' kennel is in the garden. The apostrophe is after the s when you are writing about more than one dog. (Plural possessive)

• Nouns in the plural form don't take an apostrophe. So the consultant should have written thus: In addition, I personally conduct coaching and mentorship programs for senior executives, managers and CEOs.