Add the phrase that completes a thought in
the sentence.

challenging problems

Explanation:

Whatever completes the text would have be something that relates to the problems that are to be solved as this is the subject of the sentence and it would have to be in the negatives due to the use of the word "unfortunately".

The best option is therefore the above because too many challenging problems relates to the subject of problems and is not a good thing.

the answer is "began" because it is a action that can be done

israel is a small country in the middle east about the size of the state of new jersey. the country has a diverse climate with snowy mountains in the north and the hot desert in the south. jordan, syria, and the palestinian authority all border israel to the east. lebanon serves as the northern border and egypt borders in the south.about two-thirds of the population was born in israel. all other israelis come from over 100 different countries. most israeli jews live a lifestyle similar to western europeans and north americans.israel's population is about 75 percent jewish; most of the rest is arab. the israeli-occupied palestinian territories have some 3.5 million inhabitants—about 11 percent jewish, 89 percent palestinian.because of israel's variety of terrain and climate, the country has a large variety of animals. boars roam the damp oak woodlands of the golan heights. caspian turtles live in the marshlands along the coast. and hyenas are prevalent in the negev desert region in the southern israel.israel is the only fully democratic country in the middle east. elections are held for seats in the knesset or parliament every four years. if a party wins 2 percent of the votes, the party gets one or more seats in parliament. no one party has control so they have to work together. the leader of the largest party becomes prime minister.the story of modern israel begins more than 3,500 years ago. most israelis are jews, who are said to be descended from the biblical figure abraham, through his son isaac.

(hope this and mark me as brainliest)