A commemorative speech has to do with celebrating something or someone. If you want to pay tribute to someone (and there isn't a specific topic you have to talk about), you should talk about someone important to you, someone whom you love and who inspires you - it could be a family member or a friend, or someone you look up to.
A and D both fit the definition, but i would go with A
That is a metaphor. Two things are being compared without using like or as.
Hope this helps. :)
