Cactus spines are modified
· branches
· leaves
· stems

Leaves

Explanation:

The spines of a cactus help prevent water loss by reducing air flow close to the cactus and providing some shade, while also deterring most animals that would make a meal of the cactus.

b would be the right answer

blue stars have the highest surface temp

stellar distances are usually expressed in light-years

the measure of a star's brightness is called magnitude

hope this !