Select the most appropriate option to fill in the blanks.
Digital cameras soon gained market share, gradually ________ most film camera sales to cheap, disposable, single-use models. However, with the introduction of smartphones containing ever more-advanced cameras, digital camera sales ________ by 90 percent in the 2010s.
What the passage is trying to say is that because of digital cameras, the sales of the film cameras declined, or they were forced to bring out different models it. Considering this, only Option B makes sense, as simulating, expanding or elevating most film cameras doesn't make sense.
Also, sales fall, so for the second blank too, fell is the right word.
Therefore, Option B is the correct answer.