What is the difference between chromatic, a chromosome, and a sister chromatid

Chromatin is the lose form of genetic material & the "normal state" of DNA, RNA, and protein in the nucleus and in the cells.

Chromosomes are a condensed form of chromatin. Chromatin becomes chromosomes in the Prophase of Mitosis and Prophase 1 and Prophase 2 of Meiosis. It loosens again in the Telophase in Mitosis and Telophase 1 and Telophase 2 in Meiosis.

Sister Chromatids are made when chromosomes replicate during the cell cycle. The replication leads to the formation of the chromatids. The chromatids are joined by a single centromere. They separate during Anaphase 2 of meiosis.

I hope that this helps! Sorry if it doesn't I tried my best to explain!

the two answers are a, the population of birds with large beaks will increase on the island, and c, the trait for large beaks will be passed on to future generations through natural selection. the reason for that is because if the birds that have beaks developed for eating small seeds lose all of their food, they will go hungry and eventually starve because they physically cannot eat the large seeds, therefore making the population of large beaked birds higher. also, if the trait of large beaks are dominant on the island over small beaks, then over time the large beaked birds will reproduce more and more, while the smaller beaked birds will reproduce less and less because they can't survive with the food provided. that leads to the trait of small beaks disappearing and the trait of large beaks taking over the island.