Which of the following is the cause of rising oil price?

Oil prices have risen amid growing optimism that improved US job creation will boost economic recovery and lead to higher demand for crude. In the first day of trading after the Easter break, US light crude added 1.51% to reach $86.64 a barrel. London Brent crude also went up 1.42% to $85.70 a barrel. On Friday, the US Labor Department said employers had created 162,000 new jobs in March, the highest monthly number since March 2007. However, the country’s unemployment rate remained at 9.7% for the third month in a row. World oil prices have been on an upward trend in recent weeks — partly because of signs of improvement in the US economy, but also because of a weakening dollar, which tends to increase the price of commodities priced in that currency. However, oil prices are still a long way from the record highs above $147 a barrel that they reached in July 2008.