To find the average speed of Rishi's entire journey, we need to calculate the total distance traveled and the total time taken for the journey.

Step 1: Calculate Total Distance

The total distance covered by Rishi is the sum of all the individual distances:

D_{\text{total}} = 585 \, \text{km} + 368 \, \text{km} + 168 \, \text{km}

Therefore,

D_{\text{total}} = 1121 \, \text{km}

Step 2: Calculate Total Time

The total time is the sum of the time taken for each segment of the journey.

The time for the first segment is the distance divided by speed:

T_1 = \frac{585}{65} \, \text{hours}

T_1 \approx 9 \, \text{hours} \, \text{(rounded to two decimal places: 9.00)}

The time for the second segment is:

T_2 = \frac{368}{92} \, \text{hours}

T_2 = 4 \, \text{hours}

The time for the third segment is:

T_3 = \frac{168}{56} \, \text{hours}

T_3 = 3 \, \text{hours}

The total time, T_{\text{total}}, is:

T_{\text{total}} = T_1 + T_2 + T_3 = 9 + 4 + 3 = 16 \, \text{hours}

Step 3: Calculate Average Speed

Now, use the formula for average speed:

\text{Average Speed} = \frac{D_{\text{total}}}{T_{\text{total}}}

\text{Average Speed} = \frac{1121}{16} \approx 70.0625 \, \text{km/hr}

Rounding off to two decimal places gives us:

70.06 \, \text{km/hr}

Conclusion:

The average speed for Rishi's whole journey is 70.06 \, \text{km/hr}. Therefore, the correct option is:

Option C: 70.06