Question of the day: What is agile?

What is "agile software development"?

(a) "Agile Development is a chaotic ad hoc development."
(b) "Agile Development is a product to sell. I'm a consultant and 'agile expert' and sell agile development although I do not understand the agile values and basic rules of successful together and team work. I'm the most important person in the project. I collect knowledge and do not share it as often as possible."
(c) "Agile Development means the whole team does 50 push-ups every morning before sitting at the computer."
(d) "Agile development is a set of rules and methods to increase the probability of successful finishing the IT project while having motivated engineers in real teams with respect for each other and helping peers, satisfied customers and relaxed project managers, managers and HR staff."
(e) "Agile what?"