Question
Which of the following statements are true?
A. Gravity attracts all objects towards the earth.
B. Magnetic force attracts all kinds of metals.
C. Friction always tries to prevent movement.
D. Lubricants are substances which increase friction.
E. Friction produces heat and causes wear and tear.
F. Friction can help in grinding substances.
(a) A, C, E, F are true.
(b) A, B, C, D are true.
(c) C, D, E, F are true.
(d) A, C, D, F are true.