Step-by-step Solution:

1. Determine the structure of the P₄ molecule. The P₄ molecule, known as white phosphorus, has a regular tetrahedral structure. The four phosphorus atoms are located at the vertices of the tetrahedron. Each phosphorus atom is covalently bonded to the other three phosphorus atoms.

2. Analyze the electronic configuration and bonding of a phosphorus atom. A phosphorus atom (atomic number 15) has the valence electronic configuration 3s²3p³. In the P₄ molecule, each phosphorus atom forms three single covalent bonds with its neighboring phosphorus atoms. Additionally, each phosphorus atom has one lone pair of electrons.

3. Apply VSEPR theory to determine the hybridization. To determine the hybridization of a central atom, we calculate its steric number. The steric number is the sum of the number of atoms bonded to the central atom and the number of lone pairs on it. For any phosphorus atom in the P₄ molecule:

   • Number of bonded atoms = 3
   • Number of lone pairs = 1
   • Steric Number = 3 + 1 = 4

4. Relate the steric number to hybridization. A steric number of 4 corresponds to sp³ hybridization. This means that one s orbital and three p orbitals of the phosphorus atom mix to form four equivalent sp³ hybrid orbitals. Three of these hybrid orbitals are used for forming the P-P sigma bonds, and the fourth one contains the lone pair of electrons.

5. Calculate the percentage of p-character. In an sp³ hybrid orbital, there is one part s orbital and three parts p orbitals, for a total of four parts. The fraction of p-character is the ratio of the number of p orbitals to the total number of orbitals involved in hybridization. Fraction of p-character = 3 / (1 + 3) = 3/4 To express this as a percentage: Percentage of p-character = (3/4) × 100% = 75%

6. Note on bond angles and angle strain. The ideal bond angle for sp³ hybridization is 109.5°. However, due to the tetrahedral geometry of the P₄ molecule, the internal P-P-P bond angle is constrained to 60°. This significant deviation from the ideal angle results in considerable angle strain, and the bonds are often described as "bent bonds" or "banana bonds". Despite this strain, the hybridization state is still classified as sp³ based on the count of electron domains (steric number), which is the standard approach for this level of chemistry.

Conclusion:

Based on the steric number calculation, each phosphorus atom in P₄ is sp³ hybridized. The percentage of p-character in an sp³ hybrid orbital is 75%.

Comparing this with the given options: A: 25 B: 33 C: 50 D: 75

The correct option is D.