Explanation:

Multics (Multiplexed Information and Computing Service) was a pioneering time-sharing operating system developed in the mid-1960s. It was a collaborative project involving Massachusetts Institute of Technology (MIT), General Electric (GE), and Bell Labs. Bell Labs ($ \text{d} $) played a crucial role in its development, contributing significantly to its design and implementation. Although Bell Labs eventually withdrew from the project, their initial contributions were fundamental. Option (b) Microsoft was founded much later and developed operating systems like MS-DOS and Windows. The other options are not associated with Multics development. Thus, Bell Laboratory is a correct part of its origin.