One card is drawn from a well-shuffled deck of $52$ cards. Find the probability that the card drawn is a diamond card or king.

The correct option is D: $\frac{4}{13}$
Total number of outcomes $=52$
Favourable outcomes (Diamond or a King) $=13$ diamond cards and $3$ kings other than diamond king $=16$
Probability that the card drawn is a diamond card or king $=\frac{16}{52}=\frac{4}{13}$