When a TREND is included at the end of a METAR, the trend is a forecast valid for:
a. 1 hour after the time of observation
b. 2 hours after the time of observation
c. 2 hours after it was issued
d. 1 hour after it was issued
a. 1 hour after the time of observation
b. 2 hours after the time of observation
c. 2 hours after it was issued
d. 1 hour after it was issued