Final answer:
Mr. Collins wants to marry because he perceives it as a duty of his profession, for personal happiness, and to secure property and favor with Lady Catherine de Bourgh.
Step-by-step explanation:
The three reasons Mr. Collins gives for wanting to marry are:
- He believes it is a pious duty which he owes to his profession.
- He is convinced that it will add greatly to his happiness.
- He feels assured of his property by marrying one of the daughters of his patroness, thus securing the good will of Lady Catherine de Bourgh.
These reasons reflect his self-serving nature and his regard for social status and security over affection in matters of marriage.