A/An can access all variables and methods of class.(a) datatype(c) fields(b) constructor(d) object

To answer the question correctly, let's analyze the options provided related to the accessibility of variables and methods in a class context.

Analysis of Options

1. (a) datatype: This option does not correctly match the context of class access in object-oriented programming.

2. (b) constructor: A constructor is a special method used to initialize objects but does not have access to its own class's variables or methods like an instance does.

3. (c) fields: Fields typically refer to the variables declared in the class. They are accessible via instances of the class, but this term alone does not capture the full concept.

4. (d) object: An object is an instance of a class. An instance (object) of a class can indeed access all variables (fields) and methods (including constructors) of that class.

Conclusion

Based on this analysis, the correct option that signifies what can access all variables and methods of a class is:

Final Answer

(d) object