Two employees of a company want to send data to two different colleagues at the same time. however, only one of them could send the data at that point of time. this is because the office uses a topology.

I’d say a bus topology.

Typically, only one node in a bus technology can send data at a time. In this topology, the network is occupied as long as a computer is sending data. Once the data packet arrives to its destination, the medium is free to send data. As much as nodes contend with each other, cases of collision happen more often in this kind of topology.