How are undisturbed rock layers dated

When analyzing tree rings, what do scientists assume a thin ring indicates?

Freckles are a dominant trait in humans. both of the girls have the genotype ff for freckles. if either one marries a man with no freckles, what are the chances that their children will have freckles?

Which topic is most likely to be studied by bo which topic is most likely to be studied by botanist? insect metamorphosis, viral infection, plant growth, animal physiology