Answer:
1/6 of the students in Robert's grade have both a sister and a brother.
Explanation:
Let x be the number of total students in Robert's grade.
It is given that In Robert's grade, 1/3 of the students have a sister.
Number of students have a sister = 
Of the students who have a sister, 1/2 also have a brother.
Number of students have both a sister and a brother = 
We need to find the fraction of the students in Robert's grade have both a sister and a brother.

Therefore, 1/6 of the students in Robert's grade have both a sister and a brother.
The answer is: c.it's a comment on human nature.
A strong theme usually contains a controversial thinking that could be related by most people by observing themselves and the environment surrounding them. Human nature has a very dark side to it whether we want to admit it or not. Which is why it become one of the important characteristic of a strong theme.
Answer:
A They are too large to live. C learn about meerkats. D live in the desert.
Christopher Columbus Saw Land! Early in the morning on October 12, 1492, a sailor looked out to the horizon from the bow of his sailing ship, the Pinta, and saw land. After 10 long weeks at sea, from the port of Palos, Spain, Columbus and his crews saw the New World.
The three events were:
Columbus found or landed in the Bahamas (12 Dec 1492) and in the islands of the Caribbean
Columbus sailed the ocean blue.