Analysts can use historical index data to extrapolate future returns. What is a potential shortcoming of this approach?

a.

Historical data needs to be adjusted for inflation

b.

Realised returns can provide a noisy measure of forecast returns

c.

The approach is only relevant for upward or downward trending markets

d.

An index may not be investable

e.

Calculations should not be based on long-term observation windows as investors have short term financial goals