Об­ра­зуй­те от слова EXPLORE од­но­ко­рен­ное слово так, чтобы оно грам­ма­ти­че­ски и лек­си­че­ски со­от­вет­ство­ва­ло со­дер­жа­нию тек­ста.

Up until a little over a hundred years ago the watermelon was believed to be native to Asia; then Dr. David Livingstone, the great __________________, found large tracts of wild watermelons growing in Central Africa. Authorities have now established Africa as its place of origin.