D

Step 1: Understand that the absorption of X-rays depends on the atomic number of the material; higher atomic numbers generally lead to greater absorption.
Step 2: Compare the atomic numbers of the options:

• Copper (Cu) - Atomic number 29
• Gold (Au) - Atomic number 79
• Beryllium (Be) - Atomic number 4
• Lead (Pb) - Atomic number 82

Step 3: Among these, lead has the highest atomic number, which means it has a higher density of electrons to interact with X-rays.
Step 4: Therefore, the absorption of X-rays is maximum in lead due to its high atomic number and electron density.
Therefore, the correct answer is D.