DSAT R&W: "Indeed" vs. "In Reality" (Transition Word Question) 

Here's a question from the DSAT Official Guide: Seismologists Kaiqing Yuan and Barbara Romanowicz have proposed that the magma fueling Iceland's more than 30 active volcano systems emerges from deep within the Earth. The great depths involved, nearly 3000 km, mark Iceland's volcanoes as extreme outliers;----------many of Earth's volcanoes are fed by shallow pockets of magma found less than 15 km below the surface. In the answer choices, there was only 'Indeed' and, as you can see, it was chosen as the correct answer. Here's the explanation provided by the College Board: 'Indeed' is often used to signal that the statement it introduces builds on what's been written or said previously by reaffirming the underlying truth or accuracy of these previous statements. In this sense, 'Indeed' is roughly synonymous with a phrase such as 'in reality' or 'in truth'. There's also another example where the same explanation was provided, and I believe if I'm not mistaken, there was a note that says 'Indeed' and 'in reality' most of the time can be used interchangeably. I'm probably mistaken at this point; nevertheless, I really appreciate that you made a video to explain the difference between them. Thank you!