Answer: C
Step-by-step explanation:
Answer:
The country's population decreased about 5.8 % during this time period.
Step-by-step explanation:
Population in 1990 = 164 million
Population in 2010 = 155 million
Determine the percent decrease
The formula used is: 
We have :
Initial Value = 164 million (164,000,000)
New Value = 155 million (155,000,000)
Finding percent decrease

So, The country's population decreased about 5.8 % during this time period.