Software Engineering is an engineering discipline that is concerned with:

Explanation

This is Sommerville's textbook definition: software engineering is an engineering discipline concerned with all aspects of software production, from early specification through to maintaining the system after it has gone into use. Option 1 describes computer architecture or systems knowledge, option 2 is Sommerville's definition of computer science, and option 4 is his definition of system engineering, which is the wider discipline covering hardware and process as well. The question is testing whether the candidate can separate these three neighbouring definitions, so option 3 is the intended answer.