In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: a couple spent $ 211.20 in total while dining out and paid this amount using a credit card . the $ 211.20 figure included a 20 percent tip which was paid on top of the price which already included a sales tax of 10 percent on top of the price of the food . what was the actual price of the food before tax and tip ? 
Options: a ) $ 120 , b ) $ 140 , c ) $ 150 , d ) $ 160 , e ) $ 180
Example Output: d

Example Input: Problem: 11 + 12 + 13 + . . . 51 + 52 = ? 
Options: a ) 1361 , b ) 1362 , c ) 1323 , d ) 1364 , e ) 1365
Example Output: c

Example Input: Problem: given that p is a positive even integer with a positive units digit , if the units digit of p ^ 3 minus the units digit of p ^ 2 is equal to 0 , what is the units digit of p + 4 ? 
Options: a ) 7 , b ) 8 , c ) 10 , d ) 11 , e ) 12
Example Output:
c