The time taken by the clock to strike at each hour is directly proportional to the number of strikes. At 5 o'clock, the clock strikes 5 times, and it takes 12 seconds.

To find the time for 10 o'clock, let's establish the time per strike:

Time per strike = $12$ seconds $div$ $5$ strikes = $2.4$ seconds per strike

Now, at 10 o'clock, the clock strikes 10 times:

Time taken to strike at 10 o'clock = $10$ strikes $imes$ $2.4$ seconds per strike = $24$ seconds

Answer: B. 24 seconds