How many seconds does it take to transmit lines 1 through 5?

• A. 25 seconds
• B. 15 seconds
• C. 30 seconds
• D. 45 seconds

Answer: (A)

Transmitting items one after another adds up the time for each item. If five lines are sent sequentially and each line takes five seconds to transmit, you multiply five seconds by five lines to get 25 seconds. That matches the total when there are five lines at five seconds each. The other times would require a different per-line duration or a different number of lines (for example, three seconds per line would give 15 seconds, six seconds per line would give 30 seconds, nine seconds per line would give 45 seconds).