B) herman von helmholtz
The trichromatic color theory<span> began in the 18th century, when </span>Thomas Young<span> proposed that color vision was a result of three different </span>photoreceptor cells<span>. </span>Hermann von Helmholtz<span> later expanded on Young's ideas using color-matching experiments which showed that people with normal vision needed three wavelengths to create the normal range of colors. Physiological evidence for trichromatic theory was later given by </span>Gunnar Svaetichin<span> (1956).</span>
It was carved from a bear's femur.
Answer:
The piano was invented by Bartolomeo Cristofori (1655-1731) of Italy. Cristofori was unsatisfied by the lack of control that musicians had over the volume level of the harpsichord. He is credited for switching out the plucking mechanism with a hammer to create the modern piano in around the year 1700
