Price of import goods will become relatively cheaper
Option (a) is incorrect because price of import goods will become relatively cheaper. Since demand for import goods is price elastic, quantity of import goods bought will increase more than proportionally. Thus, import expenditure will increase instead.
Option (b) is correct because less amount of Singapore dollar is needed to buy 1 unit of foreign currency so S$1 can buy more foreign currency and thus price of import goods become relatively cheaper.
Option (c) is incorrect because export goods will become relatively more expensive due to a stronger Singapore dollar as more foreign currency is needed to buy S$1
Option (d) is incorrect because when the price of export goods increases, quantity of export goods sold will decrease.