Solution:
The main question states that 20% of all employees have one year or more of an experience and no advanced degree.

First consider statement (1) alone.
35% of the employees do not have an advanced degree.
So (35-20)% or 15% of the employees have neither an advanced degree nor one or more year of experience.
Or 15% of the employees do not have an advanced degree and have less than one year of experience.
It is also given that 55% have less than one year of experience. This includes the number of people with advanced degree.
So (55-15)% or 40% have only an advanced degree and less than one year of experience.
Or statement (1) alone is sufficient to answer the question.

Next consider statement (2) alone.
15% of the employees lack an advanced degree and have less than one year of experience.
Also 45 percent have one year or more of experience.
So {100-(15+45)}% or 40% have only an advanced degree but less than one year of experience.
So statement (2) alone is also sufficient to answer the question.

The correct answer is hence (D).