The restriction on n, k and p so that PY + WY will be defined are $\cdots$

.:

Option a is correct

Given : $X_{2 \times n},Y_{3 \times k},Z_{2 \times p},W_{n \times 3},P_{p \times k}$

Now, $PY + WY = {P_{p \times k}} \times {Y_{3 \times k}} + {Q_{n \times 3}} \times {Y_{3 \times k}}$

Clearly, k = 3 and p = n