Answer:
C 200
Explanation:
It does not appear to be LINEAR so 
Start with :
pulse rate = y = 73e^kx 
sub in x = .7 when y = 155
155 = 73 e^(.7 * k) 
ln ( 155/73) = .7k 
.75296567 = .7k 
 k = 1.07567
for x = 0.9 :
pulse rate = y = 73 e^(1.07567 * .9) = ~ 192 so I expect answer is 200