I vote A for the answer to your question. Hope this helps!
The answer is B: Annotating with the pen or highlighter
When you annotate a word or a phrase in PowerPoint, you put emphasis on that word or phrase during a presentation. If something is not clear, you can always jump back to that previous point in your presentation. To annotate a phrase on your slide, right click on your slide and choose pointer options. You can either choose to use a “Pen” or a “Highlighter”
The answers are /var/lib/dhcpd/dhcpd.leases & /var/lib/dhcpd/dhcpd6.leases
In order to look up ipv4 and ipv6 dhcp leases, The two files that should be viewed are /var/lib/dhcpd/dhcpd.leases & /var/lib/dhcpd/dhcpd6.leases
Well if your talking about physically you could get some compressed air and blow it out. Or if your talking about performance you could try to re-install the os you have on it or replace the hdd with a ssd or higher performance hard disk for it to run like new. :)