Question

How many strings of four letters of the English alphabet contain exactly two vowels? O P(5,4) \cdot\left(5^{2} \cdot 21^{2}\right) 4 \cdot\left(5^{2} \cdot 21^{2}\right) P(4,2) \cdot\left(5^{2} \cdot 21^{2}\right) O None of the above

Fig: 1

Fig: 2

Fig: 3

Fig: 4

Fig: 5