The best answer is "We can expect 135 of the grandparents to spend less than 2 hours a day online" because about 54% of all people said they spend >2 hours online everyday, and 54% of 250 is 135.
Let's turn the percentages into numbers to make things easier. To find a percentage, multiply by the percentage/100, e.g. 25 percent multiply by 0.25:
250*0.54 = 135
As it happens, this is one of the answers: exactly 135 of the grandparents spend less than 2 hours online. The principle is the same for all of the other percentages. 54% of 250 is an exact number, however if a question comes up where you get a decimal answer, that is when you would select about, for example if it solved to 135.5, you cannot have .5 of a person so the answer would be about, since either 135 or 136 individuals could have watched less than two hours (the only time this should come up in the case of people, however, is if they rounded the percentage).
