What evidence indicates that plate tectonics does not occur on Venus? On Mars?

Mars has the largest volcanoes in the solar system. (T/F)

Astronomers solved this puzzle when they observed a rare transit of Venus in front of the Sun (Figure 5). What could they learn about the planet’s atmosphere from this photo?

Eventually, space telescopes have shown that Venus is shrouded by a very dense atmosphere (see Figure 6). To pierce through the dense clouds and study its surface, astronomers had to use radio imaging (see Figure 7). Venus’ atmosphere is transparent to radio waves. Research and explain briefly how, through radio imaging, Venus’ surface could be reconstructed.