The best way to find the correct answer for a sentence completion would be : find that part of the text and look for the answer.
With this , you can find the answer in a more efficient way and in a shorter amount of time
hope this helps
you could chose to describe the first graph as any of the following phrases:
‘curved graph’
‘intercept on y-axis’
‘as x increases, y increases’,
‘y increases slowly at first, then more rapidly, then slows down again’ and ‘reaches a maximum level’.
you can chose to describe the second graph as any of the following phrases:
'gradually increases, then rapidly increases in a short period of time"