C

Step 1: Analyze the assertion. The assertion states that in javelin throw, the optimal angle of projection is less than 45 degrees. This is indeed true for javelin throws to achieve maximum range while considering drag and other factors.
Step 2: Analyze the reason. The reason claims that maximum height does not depend on the angle of projection; however, this is false. The maximum height does depend on the angle, with the maximum height being achieved at a 90-degree angle.
Since the assertion is true but the reason is false, the correct option is C.