Answer:
A
Explanation:
B) Potential for human error and it takes too long to count in head
C) There is a huge gap between 1 hour and 1 minute
D) Inconvenient since it is an HOUR glass, and you can't tell when 40 minutes would be since the glass goes for a full 60 minutes
A) Best choice because there is less of a gap between a minute and a second, in comparison to an hour and a minute, therefore it is more accurate.