Without choices, we are pretty much left on our own. So I will give you what I think and you can take from that whatever you think right.
This painting is filled with interpretable figures. Begin with something easy. Father time begins on the top right and his hand extends over to the top left. The question is what does he represent so much as why is he there? My best guess is that he is suggesting that the two main figures will age, and although they are erotic and desirable now, they soon will not be.
There is a woman on the right whose face looks like a mask. It looks like she will wear one of the masks on the right. Which one will she pick: the red one for warmth or the light colored one which matches the cold lust of the two main figures? We don't know.
There is a young woman who is 1/2 snake with an upper body of someone quite beautiful. I know what she suggests to me, but I don't want to color your opinion. I am a church going person. Consider what I might think. Her face is very innocent, but her body suggests something sinister.
The only one looking on in joy is the young kid behind Venus. He's full of innocence and laughter. If you didn't know better, you would think he's out of place. You're free to say he is. But he is holding what looks like rose hips to me and he's about to throw them on Venus. He is the only thing in the painting that is taking pleasure in what is going on. Contrast him with the figure in the upper middle to left picture screaming. He I think represents the other side of the young kid.
It's a real mixed bag of interpretation. Is this part of a school project? I can't imagine it being so, but I've answered what you asked.
Answer:
A major
The last sharp in the A major scale is G#
