Which of the following is considered retrenchment under the provisions of the Industrial Disputes Act, 1947?

Section 2(oo) of Industrial Disputes Act retrenchment means the termination by the employer of the service of a workman for any reason whatsoever, otherwise than as a punishment inflicted by way of disciplinary action, but does not include- (a) voluntary retirement of the workman; or (b) retirement of the workman on reaching the age of superannuation if the contract of employment between the employer and the workman concerned contains a stipulation in that behalf; or   (bb) termination of the service of the workman as a result of the on-renewal of the contract of employment between the employer and the workman concerned on its expiry or of such contract being terminated under a stipulation in that behalf contained therein; or (c) termination of the service of a workman on the ground of continued ill-health