Explanation:

The original sentence is erroneous.

Reason: The correct idiomatic expression is 'get your fingers burned' and not 'get your burning fingers'.

Get your fingers burned (Idiom):

Meaning: To suffer unpleasant results of an action, especially loss of money, so you do not want to do the same thing again.

E.g.: She'd invested extensively in stocks and got her fingers burned when the market collapsed.

 Hence ‘get your fingers burned’ should be used in place of ‘get your fingers burning’ to make the sentence grammatically correct.

Among the given choices, only option C replaces the given bold part most appropriately.

The sentence after replacement becomes:

Investing all your money in one sector instead of diversifying your portfolio might get your fingers burned.

Option C is hence the correct answer.