Frage im Vorstellungsgespräch bei dunnhumby

basic c#, .NET core questions LINQ queries, WEP API, EF writing code for given scenarios like - How we can read large data from excel using async programming? - write a code to get the first combination from given array which will ive targeted sum? Example: array [4,6,8,5,7,3] targeted sum: 9 Expected output is 4,5 What is delegates ?