During the plague, particularly the Black Death in the 14th century, one of the primary reasons goods became more expensive was that trade routes were significantly disrupted, leading to scarcity of many goods. This scarcity was exacerbated by a high death toll, which reduced the workforce and led to higher wages for those who remained. As a result, both supply and demand dynamics contributed to higher prices.
So, the most relevant option from your list would be:
Trade routes were shut down completely and goods were scarcer.
However, it's also worth noting that the combination of the labor shortage leading to higher wages, and increased demand for some goods, also played a role in driving prices up.