@Pranavpurkar yes answer should be 1500 byte .
@Kabir5454 As you taken 10 Mbps bandwidth which are used in standard ethernet right? but in ethernet every thing is already fix means for standard ethernet distance will be 2500 m, speed will be 2 *10^8 m/s so standard propagataion delay(Tp) will be 12.5 micro second right? but here standard Tp is given in the question 26.6 micro second so what can we say Maximum or min are fix but between max & min Tp can be vary?
Ans will be 1518 bytes.1500 bytes is maximum data.