Explain why oocytes that possess a first polar body are selected for the fertilisation process.
Embryos made by IVF can be frozen in a solution containing sucrose and various salts, then later thawed and implanted. A trial was performed to compare how successful freezing oocytes was in solution A, the same solution used for freezing embryos, and solution B, a different solution with different sucrose and salt concentrations. The oocytes were put into either solution A or solution B. They were then frozen and kept at a temperature of $-33\,^{\circ}\text{C}$. Afterwards, the oocytes were thawed and then fertilised by intracytoplasmic sperm injection (ICSI).
When the oocytes were added to solution A or solution B, they rapidly decreased in size. Explain why this occurred.
Using Table 5.1, explain which solution is better to use.
Suggest one benefit of freezing and then thawing oocytes as part of the IVF procedure.