Which of the following describe a shortcoming of using hubs that is improved by instead using switches?

a. Hubs create a single electrical bus to which all devices connect, causing the
devices to share the bandwidth.
b. Hubs limit the maximum cable length of individual cables (relative to switches)
c. Hubs allow collisions to occur when two attached devices send data at the same
time.
d. Hubs restrict the number of physical ports to at most eight.