The state of the union address is given to a session of congress.
a. joint
b. special
c. conjoined
d. connected

The State of the Union address is given to a "joint" session of Congress.

A joint session of the United States Congress is a gathering of individuals from the two councils of the bicameral assembly of the national administration of the United States: the Senate and the House of Representatives. Joint sessions can be hung on any uncommon event, yet are required to be held when the President conveys a State of the Union location, when they accumulate to tally and affirm the votes of the Electoral College following a presidential decision, or when they gather on the event of a presidential initiation. A joint session is a stately or formal event and does not play out any administrative capacity; and no goals is proposed or vote taken.