Which German inventor was granted a patent for echo sounding in 1913?

The correct choice is Alexander Behm, who was granted a patent for echo sounding in 1913. Echo sounding is a critical technique used in hydrographic surveying to measure water depth by sending sound waves into the water and recording the time it takes for the echoes to return after bouncing off the seabed. This technology has played a significant role in marine navigation, seabed mapping, and environmental monitoring.

Behm’s invention allowed for the practical application of sonar technology, which has been fundamental in advancing maritime activities. Understanding the principles behind echo sounding and its historical development is essential in hydrographic surveying, as it forms the basis for many modern methodologies used in the field today.

While the other individuals listed are notable figures in their own right, they did not contribute to the development of echo sounding. Albert Einstein is known for his theoretical work in physics, particularly regarding relativity. Wilhelm Röntgen is famous for discovering X-rays, and Hermann von Helmholtz made substantial contributions in various fields, including physics and physiology, but none were directly involved with the invention of echo sounding like Behm was.