Wilkinson catalyst is:

First, we recall the well-known fact from organometallic chemistry that the Wilkinson catalyst is the standard homogeneous catalyst used for the catalytic hydrogenation of alkenes under mild conditions.

Its internationally accepted molecular formula is $$[(Ph_3P)_3RhCl]$$ where $$Ph = C_6H_5$$ (the phenyl group), $$P$$ denotes phosphorus, $$Rh$$ is rhodium, and $$Cl$$ is chloride.

Now we compare this remembered formula with each option given in the question:

Option A gives $$[(Et_3P)_3IrCl]$$. Option B gives $$[(Ph_3P)_3RhCl]$$. Option C gives $$[(Ph_3P)_3IrCl]$$. Option D gives $$[(Et_3P)_3RhCl]$$.

We see that only Option B exactly matches $$[(Ph_3P)_3RhCl]$$, the known formula of the Wilkinson catalyst. None of the other options have both the correct metal (Rh) and the correct ligand set (three triphenylphosphine groups plus chloride).

Hence, the correct answer is Option B.