The following data shows the number of students in different streams in a school: 
Which type of graph is best suited to represent this data?
Which element is a strong reducing agent in +2 oxidation state and why?

| Time (Hours) | [A] (M) |
|---|---|
| 0 | 0.40 |
| 1 | 0.20 |
| 2 | 0.10 |
| 3 | 0.05 |