Need an explaination for this 2 questions on Portfolio risk capital, contain, stocks, except, assets

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All portfolios on the capital market line are:
A) unrelated except that they all contain the risk-free asset.

B) distinct from each other.

C) perfectly positively correlated.

answer is C. why?
The market portfolio in the Capital Market Theory contains which types of investments?
A) All risky and risk-free assets in existence.

B) All stocks in existence.

C) All risky assets in existence.

Answer is C. why?