Which of the following is the description of the valuation assertion for marketable securities$?$

a$.$ The marketable securities balances include all securities transactions that have taken place during the period.

b$.$ The company has title to marketable securities accounts as of the balance sheet date.

c$.$ The recorded balances reflect the true underlying economic value of those assets.

d$.$ Marketable securities are properly classified on the balance sheet and disclosed in the notes to the financial statements.