Name the toughest subject a college student can study.
| 1 | addition | |
|---|---|---|
| 1 | subtraction | |
| 1 | numbers | |
| 1 | multiplication | |
| 1 | mathematics | |
| 1 | long division | |
| 1 | geometry | |
| 1 | fractions | |
| 1 | figures | |
| 1 | algebra | |
| 1 | trigonometry | |
| 1 | calculus | |
| 1 | division | |
| 1 | equations | |
| 2 | quantum physics | |
| 2 | physics | |
| 2 | astro physics | |
| 3 | science | |
| 3 | political science | |
| 4 | psychology | |
| 5 | sociology | |
| 6 | engineering |