The 5th deposit in a savings plan is ₹600 and the 15th deposit is ₹1000. Which pair of linear equations in the first deposit ₹a and the common difference ₹d correctly represents this situation?
a) a+5d=600,a+15d=1000
b) a+4d=600,a+14d=1000
c) a+4d=600,a+10d=1000
d) a+5d=600,a+14d=1000