Answer:
 (B)  $200,000
Step-by-step explanation:
The value of the simple interest account can be found using the formula ...
 A = P(1 +rt) . . . . . where P is the principal invested at rate r for t years
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Using the given values, we find the value of the account to be ...
 A = $125,000(1 +0.04×15) = $125,000(1.6)
 A = $200,000
Katie's savings will be worth $200,000 after 15 years.