1. ANSWER: C. tam-tam
A keyboard instrument is a musical instrument with rows of keys that is played by pressing with the use of the fingers. The tam-tam is not one of them since it looks like a gong that only needs to be hit to be played. This type of instrument is called percussion (instruments that need to be struck by the hand).
2. ANSWER: C. about 300 years ago
The modern piano was made possible shortly before the Industrial Revolution, where wires and strings were of high enough quality to be utilized. Before then, the sound of the piano wasn't as sustained and powerful, therefore bringing the design of the piano to what it is now. The modern design was ultimately planned during the period between 1660 and 1730.
3. ANSWER: B. they are struck by felt-covered hammers
This is how a piano works. The instrument has little felt-covered hammers attached to the keys (on the inside) such that when the keys are pressed, these hammers strike the strings that are found in the interior of the piano.
I have attached here a visualization of the answer in order to help you understand the process.