Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

Q: "hail to the chief" is the official presidential anthem of the united states.

A: hail to the chief
****
Q: the vektor r4 is a south african assault rifle.

A: vektor r4
****
Q: susan sontag (born susan rosenblatt, january 16, 1933 - december 28, 2004) was an american writer and political activist.

A:
susan sontag
****