Which process was occurring during some of the given stages that resulted in the formation of heavier elements
from lighter elements?
A) radiation
B) radioactive decay
C) nuclear fusion
D) conduction

i believe the answer is a.

warm front forms when a moist, warm air mass slides up and over a cold air mass. as the warm air mass rises, it condenses into a broad area of clouds. a warm front brings gentle rain or light snow, followed by warmer, milder weather.

hope i !