The frequency of brute force attacks has increased because

A.
The use of permutations and transpositions in algorithms has increased.

B.
As algorithms get stronger, they get less complex, and thus more susceptible to attacks.

C.
Processor speed and power has increased.

D.
Key length reduces over time.

Explanation:
C: A brute force attack is resource intensive. It guesses values until the correct one is obtained. As computers have more powerful processors added to them, attackers can carry out more powerful brute force attacks.