Which one is the correct answer can be more than one A hard

Which one is the correct answer? (can be more than one)

A hard real time system is a system that is always dependent on the following: Worst case execution times of tasks Deadlines that are derived from the external environment that the computer is interacting with. Consequences of not meeting the deadline are severe System programming language A/D and D/A conversion Multi-threading of tasks

Solution

Answer is 2) . Hard real system always depends on environmental conditions.