How did many twentieth-century artists respond to the extravagant furniture designs popular in the sixteenth-nineteenth centuries?
a.) by designing country-inspired pieces
b.) by designing extravagant, detailed pieces
c.) by designing asymmetrical, detailed pieces
d.) by designing simple, clean pieces

Many twentieth-century artists responded to the extravagant furniture designs popular in the sixteenth-nineteenth centuries D. by designing simple, clean pieces. Usually, each artistic era is created as a negative response to the era which preceded it and tends to do quite the opposite from what the previous epoch did. So, 19th century artists wanted to get away from the style of their predecessors, which is why they opted for simple art, rather than luxurious art that used to be created in the past.