Answer
(ii)
Work Step by Step
(see p. 875, Principle of Mathematical lnduction)
For each natural number $n$, let $P(n)$ be a statement that depends on $n$.
Suppose that each of the following conditions is satisfied.
1. $P(1)$ is true.
2. For every natural number $k$,
if $P(k)$ is true, then $P(k+1)$ is true.
Then $P(n)$ is me for all natural numbers $n$.
----------
Step 2 can be read as
P(k+1) being true follows the fact that P(k) is true.
choice (ii) is correct
