The coupling provides a secure method of transmitting which of the following from one shaft to another?

The coupling is primarily designed to connect two shafts while allowing for the effective transmission of rotational energy. This involves transmitting torque, which is the twisting force that causes rotation, and speed, which refers to how fast the rotation occurs.

When two shafts are coupled, they work together to ensure that the mechanical power is delivered efficiently from one shaft to another. The coupling's function is to maintain the alignment and ensure that the torque produced by the driving shaft is accurately transferred to the driven shaft without significant loss.

In contrast, the other options do not align with the primary function of a coupling. While some might argue that thrust can be transmitted in specific coupling types, it is not the primary purpose of a coupling. Additionally, heat is a byproduct of mechanical work and not something transmitted from one shaft to another through coupling. Distance is also not a parameter that couplings handle; they are not designed to transmit distance but rather rotational energy between connected shafts.

Thus, torque and speed are the key factors effectively managed by couplings in mechanical systems, making it the correct choice.