Your network has been having problems lately when users are participating in video conferences - the video and audio stutters very badly, to the point that the users in building 143 can't even follow what is being said. When you use OmniPeek to investigate, you discover that the link between buildings 147 and 143 is consistently at 90% usage during that period. What should be your next step

add a secondary link between buildings 147 and 143

Explanation:

Since the link is consistently showing 90% usage it means that the line is completely congested and data is being slowed due to large amounts of traffic. The best solution would be to add a secondary link between buildings 147 and 143 and divide the users between both links. That would divide the traffic and ultimately speed up the data transfer through these links drastically as they will no longer be congested.