Choose the statements which makes use of essential properties rather than making data member public in C#.NET?

[answerhappygod]

a) Properties have their own access levels like private, public, protected etc. which allows it to have better control about managing read and write properties
b) Properties give us control about what values may be assigned to a member variable of a class they represent
c) Properties consist of set accessor inside which we can validate the value before assigning it to the data variable
d) All of the mentioned