Answer:
B. 1.0g
Step-by-step explanation:
Step 1
The molarity of the solution is 0.010 M, that is, there are 0.010 moles of sodium hydroxide per liter of solution. The moles of NaOH in 2.5 L of solution are:

Step 2
The molar mass of sodium hydroxide is 40.00 g/mol. The mass corresponding to 0.025 moles is:

There is 1.0 g of NaOH in the solution.