How many devices can theoretically be connected using USB hubs?

The theoretical limit for the number of devices that can be connected using USB hubs is 127 devices. This limit is defined by the USB protocol, which stipulates that each USB hub can support a certain number of devices branching off of it. In the standard USB architecture, the host controller can connect to a maximum of 127 devices on a single bus, which includes all devices connected directly to the host and those connected through hubs.

This total of 127 devices includes the USB root hub, and the devices connected to each hub, which can recursively allow for further hub connections as long as the overall count does not exceed this limit. It's worth noting that while many devices can be connected logically, performance and bandwidth should be taken into account as they may suffer when too many devices are connected, especially if they are high-bandwidth devices.

In contrast, the other options provided reflect lower or higher limits that do not align with USB specifications.