Atomic radius a. increases across a period and increases down a group. b. decreases across a period but increases down a group. c. increases across a period but decreases down a group. d. decreases across a period and decreases down a group.

The correct answer is- B) travel horizontally.

Explanation -

As per the Newton's first law of motion, every body continues to be at state of rest or of uniform motion in a straight line unless and untill it is compelled by some external and unbalanced force.

As per the question, the ball is thrown horizontally.

If gravity did not affect the ball, it will follow horizontal path.

Thus, option B) travel horizontally is the right answer.