What process marks the birth of a star? a. a supernova explosion
b. when it begins combining hydrogen to form helium
c. when its mass expands and cools
d. when gravity pulls in nebular dust

Why does bubbling occur when vinegar mixed with baking soda

Iwill make you brainliest pleeze answer this fast i have to turn it in really soon brainliest promise easy question 6th grade ! a weather map shows a high pressure system with circles around it. what does this mean? a) an occluded front b) areas of equal altitude c) areas of equal pressure d) a stationary front

The image shows a group of fish. the type of social behavior shown in the image is called