Anything that relates to sexual reproduction (gametes coming together to fertilize) should be crossed off.
Not much context was provided but you can look back to some other questions I've answered, I have a full in-depth answer to the same question another person had.
1. Space 2
2. Back limb
3. The back limb helps because you can see the shape it was growing into and the tail because two have tails and the others don’t.
<span>Vitamin D.
Vitamin D is made from 7-dehydrocholesterol and needs UV light in order to be activated. Because the children are not exposed to sunlight, they are receiving insufficient UV light.</span>