<span>blastocyst
The outer layers of the blastocyst turn in to the trophoblast after implantation. The trophoblast forms the placenta.</span>
A star’s life expectancy depends on its mass. Generally, the more massive the star, the faster it burns up its fuel supply, and the shorter its life. The most massive stars can burn out and explode in a supernova after only a few million years of fusion. A star with a mass like the Sun, on the other hand, can continue fusing hydrogen for about 10 billion years. And if the star is very small, with a mass only a tenth that of the Sun, it can keep fusing hydrogen for up to a trillion years, longer than the current age of the universe.
I think tracheae which is B not sure tho
Because it can respire anaerobically, without oxygen.
Hope this helps!
Answer:
The answer for this is a protein D
