O-type stars
A) have lifetimes long enough for advanced life to evolve
B) have lifetimes long enough for planets to form and for life to appear, but not long enough for advanced life
C) do not contain enough heavy elements to form planets
D) have lifetimes too short for planet formation
Question 2
A force can be exerted on an object and yet do no work.
Indicate whether the statement is true or false