Use chapter 19 to support the claim, "This story is a satire ridiculing the importance of marriage to a woman's security and happiness."
The main event that occurs in Chapter 19 is the hilarious proposal that Mr Collins makes to Elizabeth. This shows definitely that Austen is satirising the importance of marriage to a woman's security and happiness, as his proposal is made in such a way that it shows firstly how ridiculous he is and secondly how little he really loves Elizabeth in any way whatsoever. Consider, for example, how he begins his proposal:
My reasons for marrying are, first, that I think it a right thing for every clergyman in easy circumstances (like myself) to set the example of matrimony in his parish. Secondly, that I am convinced it will add greatly to my happiness...
Looking at his list of reasons, Elizabeth and his love for her feature nowhere, and show him to be a very vain, shallow and selfish individual: marriage to him is about nothing more than fitting into society and pleasing himself and making his own life easier. He is even indelicate enough to mention the position of want that Elizabeth will be in if she fails to accept his proposal. Elizabeth, had she accepted him, would have gained security, but never happiness, and this is the fate that Charlotte settles for when she marries Mr Collins. In this novel therefore Austen satirises the institution of marriage as being based on gaining security, and allows her heroine to hold out until she has both security and happiness in her marriage, rather than just one or the other.