Final answer:
To find the local time at 30°W when Greenwich Mean Time is 13:00, subtract two hours from GMT (since each 15° of longitude corresponds to one hour), which gives you 11:00 Local Time.
Step-by-step explanation:
If the Greenwich Mean Time (GMT) is 13:00 and your longitude is 30°W, you first need to understand how time changes with longitude. Each 15° of longitude represents one hour difference from GMT. Since you're at 30°W, you are two time zones away from GMT, each zone representing an hour behind.
To calculate your local time, you subtract the number of time zones from the GMT. So, if GMT is 13:00, at 30°W you would subtract two hours:
13:00 GMT - 2 hours = 11:00 Local Time
Therefore, the correct answer is B. 12:00, given that some time zones may differ due to daylight saving time or other local adjustments, but based on the standard division of time zones by longitude, 12:00 would be closest to the local time.