The answer would be B. 110
The way I got this answer was due to the fact it says the average price of the other three stocks. This means they are the same price.
Now knowing this information, I did 110 x 3 which gave me 330. That is the three other stocks and now we add Drone. ( 70 )
70 + 330 = 400
now that we have 400 and 4 different stocks, to get our average we divide by 4 to give us 100.