Examine the following seismogram, which shows a 26- minute-long record of the seismic waves from the 1906 San Francisco earthquake as received by a seismograph station in Germany, over 14,000 kilometers (8,700 miles) away. Then answer the questions that follow.

1. Which letter represents the arrival of the first S waves?

2. Approximately how much time elapsed between the arrival of the first P and S waves?

a) 60 seconds

b) 4 minutes

c) 10 minutes

d) 60 minutes