Which of the following describe a shortcoming of using hubs that is improved by instead using switches?(could more than one option)

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