Correct Answer - D
From v-t graph we can analyze in `t=0` to `t=2` sec slope is positive and constant. Hence acceleration is positive and constant and it is `10/2=ms^(-2)`
Between `t=2` to `t=7` Slope is zero. Between `t=7 to `t3=10` slope is negative and constant. Hence acceleration is negative and constant and its value is `-10/3 ms^(-2)`
Hence the required at graph is (D).