Answer : The correct option is, (B) 0.25 atm
Explanation :
Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.
The combined gas equation is,

where,
= initial pressure of gas = 0.99 atm
= final pressure of gas = ?
= initial volume of gas = 2.00 L
= final volume of gas = 
= initial temperature of gas = 273 K
= final temperature of gas = 137 K
Now put all the given values in the above equation, we get:


Therefore, the final pressure of the gas is 0.25 atm.