The graph represents:

x(t)= " number of users watching a live video "

where:

t= " hours after 9:00 a.m. "

We are asked to interpret the concavity between:

t=3.2

and

t=5.7

On this interval, the graph is going downward, so the number of users is decreasing.

Also, the graph becomes steeper as it moves downward during this interval. That means the rate of decrease is becoming larger in magnitude.

In other words, the number of users is not just decreasing; it is decreasing more quickly as time passes.

So the correct interpretation is:

" The number of users is decreasing faster and faster. "

Therefore, the correct answer is:

▭ ( " C " )