In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
Q: What did the post office aid the flax mills in?, Context: During this period, the island enjoyed increased revenues through the sale of flax, with prices peaking in 1951. However, the industry declined because of transportation costs and competition from synthetic fibres. The decision by the British Post Office to use synthetic fibres for its mailbags was a further blow, contributing to the closure of the island's flax mills in 1965.
A:
closure