Explanation:

The correct option is (e) All of these can be purchased. Let's analyze each option: (a) 'Off-the-shelf' software (also known as Commercial Off-The-Shelf or COTS) is mass-produced, readily available software that is explicitly designed to be bought and used immediately. (b) 'Tailor-made' software is custom-built for a specific client's unique requirements, and the client pays for its development and ownership, meaning it is bought. (c) 'Custom-developed' software is synonymous with tailor-made software; it is commissioned and paid for by a client, hence purchased. (d) 'Off-the-shelf with alterations' implies purchasing existing software and then paying for additional modifications or customizations, which clearly involves buying both the base software and the alteration services. Since all the preceding options describe types of software that are acquired through purchase, the statement that 'All of these can be purchased' is correct.