Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Problem: o ( x ) represents the least odd integer greater than x, whereas o ( x ) represents the greatest odd integer less than x. likewise, e ( x ) represents the least even integer greater than x, whereas e ( x ) represents the greatest even integer less than x. according to these definitions, the value of o ( 5.3 ) + e ( 6.7 ) + o ( 7.3 ) + e ( 6.6 ) is :
Options: a. - 4, b. - 2, c. 0, d. 2, e. 4
b