Statement ""IN ANY ITERATION ,THE SHORTEST PATH TO A VERTEX V IS UPDATED ONLY WHEN A STRICTLY SHORTEST PATH TO V IS DISCOVERED"""
that means we have to considered only such node whose relaxation can affect/reduces /(changes to min. value than earlier) other neighbouring nodes along with that it must be in shortest path( i.e. while relaxation of D it reduces the node value of F but cant reduces the value of T , therefore it is not considered)