The table below shows a consumer's total utility from consuming consecutive units of a specific good.
| Unit of Consumption | Total Utility (utils) |
|---|---|
| 1 | 18 |
| 2 | 38 |
| 3 | 60 |
| 4 | 78 |
| 5 | 92 |
| 6 | 102 |
| 7 | 108 |
At which unit of consumption does the consumer begin to experience diminishing marginal utility?
3
4
5
6
